Chapter XXXII: Some Simple Organic Compounds

~Division of chemistry into organic and inorganic.~ Chemistry is usually divided into two great divisions,--organic and inorganic. The original significance of these terms was entirely different from the meaning which they have at the present time.

1. _Original significance._ The division into organic and inorganic was originally made because it was believed that those substances which constitute the essential parts of living organisms were built up under the influence of the life force of the organism. Such substances, therefore, should be regarded as different from those compounds prepared in the laboratory or formed from the inorganic or mineral constituents of the earth. In accordance with this view organic chemistry included those substances formed by living organisms. Inorganic chemistry, on the other hand, included all substances formed from the mineral portions of the earth.

In 1828 the German chemist Wöhler prepared urea, a typical organic compound, from inorganic materials. The synthesis of other so-called organic compounds followed, and at present it is known that the same chemical laws apply to all substances whether formed in the living organism or prepared in the laboratory from inorganic constituents. The terms "organic" and "inorganic" have therefore lost their original significance.

2. _Present significance._ The great majority of the compounds found in living organisms contain carbon, and the term "organic chemistry," as used at present, includes not only these compounds but all compounds of carbon. _Organic chemistry_ has become, therefore, _the chemistry of the compounds of carbon_, all other substances being treated under the head of inorganic chemistry. This separation of the compounds of carbon into a group by themselves is made almost necessary by their great number, over one hundred thousand having been recorded. For convenience some of the simpler carbon compounds, such as the oxides and the carbonates, are usually discussed in inorganic chemistry.

~The grouping of compounds in classes.~ The study of organic chemistry is much simplified by the fact that the large number of bodies included in this field may be grouped in classes of similar compounds. It thus becomes possible to study the properties of each class as a whole, in much the same way as we study a group of elements. The most important of these classes are the _hydrocarbons_, the _alcohols_, the _aldehydes_, the _acids_, the _ethereal salts_, the _ethers_, the _ketones_, the _organic bases_, and the _carbohydrates_. A few members of each of these classes will now be discussed briefly.

THE HYDROCARBONS

Carbon and hydrogen combine to form a large number of compounds. These compounds are known collectively as the _hydrocarbons_. They may be divided into a number of groups or series, each being named from its first member. Some of the groups are as follows:

METHANE SERIES
CH_{4} methane
C_{2}H_{6} ethane
C_{3}H_{8} propane
C_{4}H_{10} butane
C_{5}H_{12} pentane
C_{6}H_{14} hexane
C_{7}H_{16} heptane
C_{8}H_{18} octane

ETHYLENE SERIES
C_{2}H_{4} ethylene
C_{3}H_{6} propylene
C_{4}H_{8} butylene

BENZENE SERIES
C_{6}H_{6} benzene
C_{7}H_{8} toluene
C_{8}H_{10} xylene

ACETYLENE SERIES
C_{2}H_{2} acetylene
C_{3}H_{4} allylene

Only the lower members (that is, those which contain a small number of carbon atoms) of the above groups are given. The methane series is the most extensive, all of the compounds up to C_{24}H_{50} being known.

It will be noticed that the successive members of each of the above series differ by the group of atoms (CH_{2}). Such a series is called an _homologous series_. In general, it may be stated that the members of an homologous series show a regular gradation in most physical properties and are similar in chemical properties. Thus in the methane group the first four members are gases at ordinary temperatures; those containing from five to sixteen carbon atoms are liquids, the boiling points of which increase with the number of carbon atoms present. Those containing more than sixteen carbon atoms are solids.

~Sources of the hydrocarbons.~ There are two chief sources of the hydrocarbons, namely, (1) crude petroleum and (2) coal tar.

1. _Crude petroleum._ This is a liquid pumped from wells driven into the earth in certain localities. Pennsylvania, Ohio, Kansas, California, and Texas are the chief oil-producing regions in the United States. The crude petroleum consists largely of liquid hydrocarbons in which are dissolved both gaseous and solid hydrocarbons. Before being used it must be refined. In this process the petroleum is run into large iron stills and subjected to fractional distillation. The various hydrocarbons distill over in the general order of their boiling points. The distillates which collect between certain limits of temperature are kept separate and serve for different uses; they are further purified, generally by washing with sulphuric acid, then with an alkali, and finally with water. Among the products obtained from crude petroleum in this way are the naphthas, including benzine and gasoline, kerosene or coal oil, lubricating oils, vaseline, and paraffin. None of these products are definite chemical compounds, but each consists of a mixture of hydrocarbons, the boiling points of which lie within certain limits.

2. _Coal tar._ This product is obtained in the manufacture of coal gas, as already explained. It is a complex mixture and is refined by the same general method used in refining crude petroleum. The principal hydrocarbons obtained from the coal tar are benzene, toluene, naphthalene, and anthracene. In addition to the hydrocarbons, coal tar contains many other compounds, such as carbolic acid and aniline.

~Properties of the hydrocarbons.~ The lower members of the first two series of hydrocarbons mentioned are all gases; the succeeding members are liquids. In some series, as the methane series, the higher members are solids. The preparation and properties of methane and acetylene have been discussed in a previous chapter. Ethylene is present in small quantities in coal gas and may be obtained in the laboratory by treating alcohol (C_{2}H_{6}O) with sulphuric acid:

C_{2}H_{6}O = C_{2}H_{4} + H_{2}O.

Benzene, the first member of the benzene series, is a liquid boiling at 80°.

The hydrocarbons serve as the materials from which a large number of compounds can be prepared; indeed, it has been proposed to call organic chemistry _the chemistry of the hydrocarbon derivatives_.

~Substitution products of the hydrocarbons.~ As a rule, at least a part of the hydrogen in any hydrocarbon can be displaced by an equivalent amount of certain elements or groups of elements. Thus the compounds CH_{3}Cl, CH_{2}Cl_{2}, CHCl_{3}, CCl_{4} can be obtained from methane by treatment with chlorine. Such compounds are called _substitution products_.

~Chloroform~ (CHCl_{3}). This can be made by treating methane with chlorine, as just indicated, although a much easier method consists in treating alcohol or acetone (which see) with bleaching powder. Chloroform is a heavy liquid having a pleasant odor and a sweetish taste. It is largely used as a solvent and as an anæsthetic in surgery.

~Iodoform~ (CHI_{3}). This is a yellow crystalline solid obtained by treating alcohol with iodine and an alkali. It has a characteristic odor and is used as an antiseptic.

ALCOHOLS

When such a compound as CH_{3}Cl is treated with silver hydroxide the reaction expressed by the following equation takes place:

CH_{3}Cl + AgOH = CH_{3}OH + AgCl.

Similarly C_{2}H_{5}Cl will give C_{2}H_{5}OH and AgCl. The compounds CH_{3}OH and C_{2}H_{5}OH so obtained belong to the class of substances known as _alcohols_. From their formulas it will be seen that they may be regarded as derived from hydrocarbons by substituting the hydroxyl group (OH) for hydrogen. Thus the alcohol CH_{3}OH may be regarded as derived from methane (CH_{4}) by substituting the group OH for one atom of hydrogen. A great many alcohols are known, and, like the hydrocarbons, they may be grouped into series. The relation between the first three members of the methane series and the corresponding alcohols is shown in the following table:

CH_{4} (methane) CH_{3}OH (methyl alcohol).
C_{2}H_{6} (ethane) C_{2}H_{5}OH (ethyl alcohol).
C_{3}H_{8} (propane) C_{3}H_{7}OH (propyl alcohol).

~Methyl alcohol~ (_wood alcohol_) (CH_{3}OH). When wood is placed in an air-tight retort and heated, a number of compounds are evolved, the most important of which are the three liquids, methyl alcohol, acetic acid, and acetone. Methyl alcohol is obtained entirely from this source, and on this account is commonly called _wood alcohol_. It is a colorless liquid which has a density of 0.79 and boils at 67°. It burns with an almost colorless flame and is sometimes used for heating purposes, in place of the more expensive ethyl alcohol. It is a good solvent for organic substances and is used especially as a solvent in the manufacture of varnishes. It is very poisonous.

~Ethyl alcohol~ (_common alcohol_) (C_{2}H_{5}OH). 1. _Preparation._ This compound may be prepared from glucose (C_{6}H_{12}O_{6}), a sugar easily obtained from starch. If some baker's yeast is added to a solution of glucose and the temperature is maintained at about 30°, bubbles of gas are soon evolved, showing that a change is taking place. The yeast contains a large number of minute organized bodies, which are really forms of plant life. The plant grows in the glucose solution, and in so doing secretes a substance known as _zymase_, which breaks down the glucose in accordance with the following equation:

C_{6}H_{12}O_{6} = 2C_{2}H_{5}OH + 2CO_{2}.

~Laboratory preparation of alcohol.~ The formation of alcohol and
carbon dioxide from glucose may be shown as follows: About 100
g. of glucose are dissolved in a liter of water in flask A
(Fig. 90). This flask is connected with the bottle B, which
is partially filled with limewater. The tube C contains solid
sodium hydroxide. A little baker's yeast is now added to the
solution in flask A, and the apparatus is connected, as shown
in the figure. If the temperature is maintained at about 30°,
the reaction soon begins. The bubbles of gas escape through the
limewater in B. A precipitate of calcium carbonate soon forms
in the limewater, showing the presence of carbon dioxide. The
sodium hydroxide in tube C prevents the carbon dioxide in the
air from acting on the limewater. The alcohol remains in the
flask A and may be separated by fractional distillation.

2. _Properties._ Ethyl alcohol is a colorless liquid with a pleasant odor. It has a density of 0.78 and boils at 78°. It resembles methyl alcohol in its general properties. It is sometimes used as a source of heat, since its flame is very hot and does not deposit carbon, as the flame from oil does. When taken into the system in small quantities it causes intoxication; in larger quantities it acts as a poison. The intoxicating properties of such liquors as beer, wine, and whisky are due to the alcohol present. Beer contains from 2 to 5% of alcohol, wine from 5 to 20%, and whisky about 50%. The ordinary alcohol of the druggist contains 94% of alcohol and 6% of water. When this is boiled with lime and then distilled nearly all the water is removed, the distillate being called _absolute alcohol_.

~Commercial preparation of alcohol.~ Alcohol is prepared
commercially from starch obtained from corn or potatoes. The
starch is first converted into a sugar known as maltose, by the
action of _malt_, a substance prepared by moistening barley
with water, allowing it to germinate, and then drying it. There
is present in the malt a substance known as diastase, which has
the property of changing starch into maltose. This sugar, like
glucose, breaks down into alcohol and carbon dioxide in the
presence of yeast. The resulting alcohol is separated by
fractional distillation.

~Denatured alcohol.~ The 94% alcohol is prepared at present at a
cost of about 35 cents per gallon, which is about half the cost
of the preparation of methyl alcohol. The government, however,
imposes a tax on all ethyl alcohol which amounts to $2.08 per
gallon on the 94% product. This increases its cost to such an
extent that it is not economical to use it for many purposes
for which it is adapted, such as a solvent in the preparation
of paints and varnishes and as a material for the preparation
of many important organic compounds. By an act of Congress in
1906, the tax was removed from _denatured_ alcohol, that is
alcohol mixed with some substance which renders it unfit for
the purposes of a beverage but will not impair its use for
manufacturing purposes. Some of the European countries have
similar laws. The substances ordinarily used to denature
alcohol are wood alcohol and pyridine, the latter compound
having a very offensive odor.

~Fermentation.~ The reaction which takes place in the preparation
of ethyl alcohol belongs to the class of changes known under
the general name of fermentation. Thus we say that the yeast
causes the glucose to ferment, and the process is known as
alcoholic fermentation. There are many kinds of fermentations,
and each is thought to be due to the presence of a definite
substance known as an _enzyme_, which acts by catalysis. In
many cases, as in alcoholic fermentation, the change is brought
about by the action of minute forms of life. These probably
secrete the enzymes which cause the fermentation to take place.
Thus the yeast plant is supposed to bring about alcoholic
fermentation by secreting the enzyme known as zymase.

~Glycerin~ (C_{3}H_{5}(OH)_{3}). This compound may be regarded as derived from propane (C_{3}H_{8}) by displacing three atoms of hydrogen by three hydroxyl groups, and must therefore be regarded as an alcohol. It is formed in the manufacture of soaps, as will be explained later. It is an oily, colorless liquid having a sweetish taste. It is used in medicine and in the manufacture of the explosives nitroglycerin and dynamite.

ALDEHYDES

When alcohols are treated with certain oxidizing agents two hydrogen atoms are removed from each molecule of the alcohol. The resulting compounds are known as aldehydes. The relation of the aldehydes derived from methyl and ethyl alcohol to the alcohols themselves may be shown as follows:

Alcohols {CH_{3}OH Corresponding aldehydes {CH_{2}O
{C_{2}H_{5}OH {C_{2}H_{4}O

The first of these (CH_{2}O) is a gas known as formaldehyde. Its aqueous solution is largely used as an antiseptic and disinfectant under the name of _formalin_. Acetaldehyde (C_{2}H_{4}O) is a liquid boiling at 21°.

ACIDS

Like the other classes of organic compounds, the organic acids may be arranged in homologous series. One of the most important of these series is the _fatty-acid series_, the name having been given to it because the derivatives of certain of its members are constituents of the fats. Some of the most important members of the series are given in the following table. They are all monobasic, and this fact is expressed in the formulas by separating the replaceable hydrogen atom from the rest of the molecule:

H·CHO_{2} formic acid, a liquid boiling at 100°.
H·C_{2}H_{3}O acetic acid, a liquid boiling at 118°.
H·C_{3}H_{5}O_{2} propionic acid, a liquid boiling at 140°.
H·C_{4}H_{7}O_{2} butyric acid, a liquid boiling at 163°.
H·C_{16}H_{31}O_{2} palmitic acid, a solid melting at 62°.
H·C_{18}H_{35}O_{2} stearic acid, a solid melting at 69°.

~Formic acid~ (H·CHO_{2}). The name "formic" is derived from the Latin _formica_, signifying ant. This name was given to the acid because it was formerly obtained from a certain kind of ants. It is a colorless liquid and occurs in many plants such as the stinging nettles. The inflammation caused by the sting of the bee is due to formic acid.

~Acetic acid~ (H·C_{2}H_{3}O_{2}). Acetic acid is the acid present in vinegar, the sour taste being due to it. It can be prepared by either of the following methods.

1. _Acetic fermentation._ This consists in the change of alcohol into acetic acid through the agency of a minute organism commonly called mother of vinegar. The change is represented by the following equation:

C_{2}H_{5}OH + 2O = HC_{2}H_{3}O_{2} + H_{2}O.

The various kinds of vinegars are all made by this process. In the manufacture of cider vinegar the sugar present in the cider first undergoes alcoholic fermentation; the resulting alcohol then undergoes acetic fermentation. The amount of acetic acid present in vinegars varies from 3 to 6%.

2. _From the distillation of wood._ The liquid obtained by heating wood in the absence of air contains a large amount of acetic acid, and this can be separated readily in a pure state. This is the most economical method for the preparation of the concentrated acid.

Acetic acid is a colorless liquid and has a strong pungent odor. Many of its salts are well-known compounds. Lead acetate (Pb(C_{2}H_{3}O_{2})_{2}) is the ordinary _sugar of lead_. Sodium acetate (NaC_{2}H_{3}O_{2}) is a white solid largely used in making chemical analyses. Copper acetate (Cu(C_{2}H_{3}O_{2})_{2}) is a blue solid. When copper is acted upon by acetic acid in the presence of air a green basic acetate of copper is formed. This is commonly known as verdigris. All acetates are soluble in water.

~Butyric acid~ (H·C_{4}H_{7}O_{2}). Derivatives of butyric acid are present in butter and impart to it its characteristic flavor.

~Palmitic and stearic acids.~ Ordinary fats consist principally of derivatives of palmitic and stearic acids. When the fats are heated with sodium hydroxide the sodium salts of these acids are formed. If hydrochloric acid is added to a solution of the sodium salts, the free palmitic and stearic acids are precipitated. They are white solids, insoluble in water. Stearic acid is often used in making candles.

~Acids belonging to other series.~ In addition to members of the fatty-acid series, mention may be made of the following well-known acids.

~Oxalic acid~ (H_{2}C_{2}O_{4}). This is a white solid which occurs in nature in many plants, such as the sorrels. Its ammonium salt ((NH_{4})_{2}C_{2}O_{4}) is used as a reagent for the detection of calcium. When added to a solution of a calcium compound the white, insoluble calcium oxalate (CaC_{2}O_{4}) precipitates.

~Tartaric acid~ (H_{2}·C_{4}H_{4}O_{6}). This compound occurs either in a free state or in the form of its salts in many fruits. The potassium acid salt (KHC_{4}H_{4}O_{6}) occurs in the juice of grapes. When the juice ferments in the manufacture of wine, this salt, being insoluble in alcohol, separates out on the sides of the cask and in this form is known as argol. This is more or less colored by the coloring matter of the grape. When purified it forms a white solid and is sold under the name of cream of tartar. The following are also well-known salts of tartaric acid: potassium sodium tartrate (Rochelle salt) (KNaC_{4}H_{4}O_{6}), potassium antimonyl tartrate (tartar emetic) (KSbOC_{4}H_{4}O_{6}).

~Cream of tartar baking powders.~ The so-called cream of tartar
baking powders consist of a mixture of cream of tartar,
bicarbonate of soda, and some starch or flour. When water is
added to this mixture the cream of tartar slowly acts upon the
soda present liberating carbon dioxide in accordance with the
following equation:

KHC_{4}H_{4}O_{6} + NaHCO_{3} = KNaC_{4}H_{4}O_{6} + H_{2}O +
CO_{2}.

The carbon dioxide evolved escapes through the dough, thus
making it light and porous.

~Citric acid~ (H_{3}·C_{6}H_{5}O_{7}). This acid occurs in many fruits, especially in lemons. It is a white solid, soluble in water, and is often used as a substitute for lemons in making lemonade.

~Lactic acid~ (H·C_{3}H_{5}O_{3}). This is a liquid which is formed in the souring of milk.

~Oleic acid~ (H·C_{18}H_{33}O_{2}). The derivatives of this acid constitute the principal part of many oils and liquid fats. The acid itself is an oily liquid.

ETHEREAL SALTS

When acids are brought in contact with alcohols under certain conditions a reaction takes place similar to that which takes place between acids and bases. The following equations will serve as illustrations:

KOH + HNO_{3} = KNO_{3} + H_{2}O,

CH_{3}OH + HNO_{3} = CH_{3}NO_{3} + H_{2}O.

The resulting compounds of which methyl nitrate (CH_{3}NO_{3}) may be taken as the type belong to the class known as _ethereal salts_, the name having been given them because some of them possess pleasant ethereal odors. It will be seen that the ethereal salts differ from ordinary salts in that they contain a hydrocarbon radical, such as CH_{3}, C_{2}H_{5}, C_{3}H_{5}, in place of a metal.

~The nitrates of glycerin~ (_nitroglycerin_). Nitric acid reacts with glycerin in the same way that it reacts with a base containing three hydroxyl groups such as Fe(OH)_{3}:

Fe(OH)_{3} + 3HNO_{3} = Fe(NO_{3})_{3} + 3H_{2}O,

C_{3}H_{5}(OH)_{3} + 3HNO_{3} = C_{3}H_{5}(NO_{3})_{3} + 3H_{2}O.

The resulting nitrate (C_{3}H_{5}(NO_{3})_{3}) is the main constituent of _nitroglycerin_, a slightly yellowish oil characterized by its explosive properties. Dynamite consists of porous earth which has absorbed nitroglycerin, and its strength depends on the amount present. It is used much more largely than nitroglycerin itself, since it does not explode so readily by concussion and hence can be transported with safety.

~The fats.~ These are largely mixtures of the ethereal salts known respectively as olein, palmitin, and stearin. These salts may be regarded as derived from oleic, palmitic, and stearic acids respectively, by replacing the hydrogen of the acid with the glycerin radical C_{3}H_{5}. Since this radical is trivalent and oleic, palmitic, and stearic acids contain only one replaceable hydrogen atom to the molecule, it is evident that three molecules of each acid must enter into each molecule of the ethereal salt. The formulas for the acids and the ethereal salts derived from each are as follows:

HC_{18}H_{33}O_{2} (oleic acid)
C_{8}H_{6}(C_{18}H_{33}O_{2})_{3}, (olein)

HC_{16}H_{31}O_{2} (palmitic acid)
C_{3}H_{5}(C_{16}H_{31}0_{2})_{3} (palmitin)

HC_{18}H_{35}O_{2} (stearic acid)
C_{3}H_{5}(C_{18}H_{35}O_{2})_{3} (stearin)

Olein is a liquid and is the main constituent of liquid fats. Palmitin and stearin are solids.

~Butter fat and oleomargarine.~ Butter fat consists principally of olein, palmitin, and stearin. The flavor of the fat is due to the presence of a small amount of butyrin, which is an ethereal salt of butyric acid. Oleomargarine differs from butter mainly in the fact that a smaller amount of butyrin is present. It is made from the fats obtained from cattle and hogs. This fat is churned up with milk, or a small amount of butter is added, in order to furnish sufficient butyrin to impart the butter flavor.

~Saponification.~ When an ethereal salt is heated with an alkali a reaction expressed by the following equation takes place:

C_{2}H_{5}NO_{3} + KOH = C_{2}H_{5}OH + KNO_{3}.

This process is known as _saponification_, since it is the one which takes place in the manufacture of soaps. The ordinary soaps are made by heating fats with a solution of sodium hydroxide. The reactions involved may be illustrated by the following equation representing the reaction between palmitin and sodium hydroxide:

C_{3}H_{5}(C_{16}H_{31}O_{2})_{3} + 3 NaOH
= 3 NaC_{16}H_{31}O_{2} + C_{3}H_{5}(OH)_{3}.

In accordance with this equation the ethereal salts in the fats are converted into glycerin and the sodium salts of the corresponding acids. The sodium salts are separated and constitute the soaps. These salts are soluble in water. When added to water containing calcium salts the insoluble calcium palmitate and stearate are precipitated. Magnesium salts act in a similar way. It is because of these facts that soap is used up by hard waters.

ETHERS

When ethyl alcohol is heated to 140° with sulphuric acid the reaction expressed by the following equation takes place:

2C_{2}H_{5}OH = (C_{2}H_{5})_{2}O + H_{2}O.

The resulting compound, (C_{2}H_{5})_{2}O, is ordinary ether and is the most important member of the class of compounds called _ethers_. Ordinarily ether is a light, very inflammable liquid boiling at 35°. It is used as a solvent for organic substances and as an anæsthetic in surgical operations.

KETONES

The most common member of this group is acetone (C_{3}H_{6}O), a colorless liquid obtained when wood is heated in the absence of air. It is used in the preparation of other organic compounds, especially chloroform.

ORGANIC BASES

This group includes a number of compounds, all of which contain nitrogen as well as carbon. They are characterized by combining directly with acids to form salts, and in this respect they resemble ammonia. They may, indeed, be regarded as derived from ammonia by displacing a part or all of the hydrogen present in ammonia by hydrocarbon radicals. Among the simplest of these compounds may be mentioned methylamine (CH_{3}NH_{2}) and ethylamine (C_{2}H_{5}NH_{2}). These two compounds are gases and are formed in the distillation of wood and bones. Pyridine (C_{5}H_{6}N) and quinoline (C_{9}H_{7}N) are liquids present in small amounts in coal tar, and also in the liquid obtained by the distillation of bones. Most of the compounds now classified under the general name of _alkaloids_ (which see) also belong to this group.

CARBOHYDRATES

The term "carbohydrate" is applied to a class of compounds which includes the sugars, starch, and allied bodies These compounds contain carbon, hydrogen, and oxygen the last two elements generally being present in the proportion in which they combine to form water. The most important members of this class are the following:

Cane sugar C_{12}H_{22}O_{11}.
Milk sugar C_{12}H_{22}O_{11}.
Dextrose C_{6}H_{12}O_{6}.
Levulose C_{6}H_{12}O_{6}.
Cellulose C_{6}H_{10}O_{5}.
Starch C_{6}H_{10}0_{5}.

~Cane sugar~ (C_{12}H_{22}O_{11}). This is the well-known substance commonly called sugar. It occurs in many plants especially in the sugar cane and sugar beet. It was formerly obtained almost entirely from the sugar cane, but at present the greatest amount of it comes from the sugar beet. The juice from the cane or beet contains the sugar in solution along with many impurities. These impurities are removed, and the resulting solution is then evaporated until the sugar crystallizes out. The evaporation is conducted in closed vessels from which the air is partially exhausted. In this way the boiling point of the solution is lowered and the charring of the sugar is prevented. It is impossible to remove all the sugar from the solution. In preparing sugar from sugar cane the liquors left after separating as much of it as possible from the juice of the cane constitute ordinary molasses. Maple sugar is made by the evaporation of the sap obtained from a species of the maple tree. Its sweetness is due to the presence of cane sugar, other products present in the maple sap imparting the distinctive flavor.

When a solution of cane sugar is heated with hydrochloric or other dilute mineral acid, two compounds, dextrose and levulose, are formed in accordance with the following equation:

C_{12}H_{22}O_{11} + H_{2}O = C_{6}H_{12}O_{6} + C_{6}H_{12}O_{6}.

This same change is brought about by the action of an enzyme present in the yeast plant. When yeast is added to a solution of cane sugar fermentation is set up. The cane sugar, however, does not ferment directly: the enzyme in the yeast first transforms the sugar into dextrose and levulose, and these sugars then undergo alcoholic fermentation.

When heated to 160° cane sugar melts; if the temperature is increased to about 215°, a partial decomposition takes place and a brown substance known as caramel forms. This is used largely as a coloring matter.

~Milk sugar~ (C_{12}H_{22}O_{11}). This sugar is present in the milk of all mammals. The average composition of cow's milk is as follows:

Water 87.17%
Casein (nitrogenous matter) 3.56
Butter fat 3.64
Milk sugar 4.88
Mineral matter 0.75

When _rennin_, an enzyme obtained from the stomach of calves, is added to milk, the casein separates and is used in the manufacture of cheese. The remaining liquid contains the milk sugar which separates on evaporation; it resembles cane sugar in appearance but is not so sweet or soluble. The souring of milk is due to the fact that the milk sugar present undergoes _lactic fermentation_ in accordance with the equation

C_{12}H_{22}O_{11} + H_{2}O = 4C_{3}H_{6}O_{3}.

The lactic acid formed causes the separation of the casein, thus giving the well-known appearance of sour milk.

~Isomeric compounds.~ It will be observed that cane sugar and milk sugar have the same formulas. Their difference in properties is due to the different arrangement of the atoms in the molecule. Such compounds are said to be isomeric. Dextrose and levulose are also isomeric.

~Dextrose~ (_grape sugar, glucose_) (C_{6}H_{12}O_{6}). This sugar is present in many fruits and is commonly called grape sugar because of its presence in grape juice. It can be obtained by heating cane sugar with dilute acids, as explained above; also by heating starch with dilute acids, the change being as follows:

C_{6}H_{10}6_{5} + H_{2}O = C_{6}H_{12}O_{6}.

Pure dextrose is a white crystalline solid, readily soluble in water, and is not so sweet as cane sugar. In the presence of yeast it undergoes alcoholic fermentation. It is prepared from starch in large quantities, and being less expensive than cane sugar, is used as a substitute for it in the manufacture of jellies, jams, molasses, candy, and other sweets. The product commonly sold under the name of _glucose_ contains about 45% of dextrose.

~Levulose~ _(fruit sugar)_(C_{6}H_{12}O_{6}). This sugar is a white solid which occurs along with dextrose in fruits and honey. It undergoes alcoholic fermentation in the presence of yeast.

~Cellulose~ (C_{6}H_{10}O_{5}). This forms the basis of all woody fibers. Cotton and linen are nearly pure cellulose. It is insoluble in water, alcohol, and dilute acids. Sulphuric acid slowly converts it into dextrose. Nitric acid forms nitrates similar to nitroglycerin in composition and explosive properties. These nitrates are variously known as nitrocellulose, pyroxylin, and gun cotton. When exploded they yield only colorless gases; hence they are used especially in the manufacture of smokeless gunpowder. _Collodion_ is a solution of nitrocellulose in a mixture of alcohol and ether. _Celluloid_ is a mixture of nitrocellulose and camphor. _Paper_ consists mainly of cellulose, the finer grades being made from linen and cotton rags, and the cheaper grades from straw and wood.

~Starch~ (C_{6}H_{10}O_{5}). This is by far the most abundant carbohydrate found in nature, being present especially in seeds and tubers. In the United States it is obtained chiefly from corn, nearly 80% of which is starch. In Europe it is obtained principally from the potato. It consists of minute granules and is practically insoluble in cold water. These granules differ somewhat in appearance, according to the source of the starch, so that it is often possible to determine from what plant the starch was obtained. When heated with water the granules burst and the starch partially dissolves. Dilute acids, as well as certain enzymes, convert it into dextrose or similar sugars. When seeds germinate the starch present is converted into soluble sugars, which are used as food for the growing plant.

~Chemical changes in bread making.~ The average composition of wheat flour is as follows:

Water. 13.8%
Protein (nitrogenous matter) 7.9
Fats 1.4
Starch 76.4
Mineral matter 0.5

In making bread the flour is mixed with water and yeast, and the resulting dough set aside in a warm place for a few hours. The yeast first converts a portion of the starch into dextrose or a similar sugar, which then undergoes alcoholic fermentation. The carbon dioxide formed escapes through the dough, making it light and porous. The yeast plant thrives best at about 30°; hence the necessity for having the dough in a warm place. If the temperature rises above 50°, the vitality of the yeast is destroyed and fermentation ceases. In baking the bread, the heat expels the alcohol and also expands the bubbles of carbon dioxide caught in the dough, thus increasing its lightness.

SOME DERIVATIVES OF BENZENE

Attention has been called to the complex nature of coal tar. Among the compounds present are the hydrocarbons, benzene, toluene, naphthalene, and anthracene. These compounds are not only useful in themselves but serve for the preparation of many other important compounds known under the general name of coal-tar products.

~Nitrobenzene~ (_oil of myrbane_) (C_{6}H_{5}NO_{2}). When benzene is treated with nitric acid a reaction takes place which is expressed by the following equation:

C_{6}H_{6} + HNO_{3} = C_{6}H_{5}NO_{2} + H_{2}O.

The product C_{6}H_{5}NO_{2} is called nitrobenzene. It is a slightly yellowish poisonous liquid, with a characteristic odor. Its main use is in the manufacture of aniline.

~Aniline~ (C_{6}H_{5}NH_{2}). When nitrobenzene is heated with iron and hydrochloric acid the hydrogen evolved by the action of the iron upon the acid reduces the nitrobenzene in accordance with the following equation:

C_{6}H_{5}NO_{2} + 6H = C_{6}H_{5}NH_{2} + 2H_{2}O.

The resulting compound is known as aniline, a liquid boiling at 182°. When first prepared it is colorless, but darkens on standing. Large quantities of it are used in the manufacture of the _aniline or coal-tar dyes_, which include many important compounds.

~Carbolic acid~ (C_{6}H_{5}OH). This compound, sometimes known as _phenol_, occurs in coal tar, and is also prepared from benzene. It forms colorless crystals which are very soluble in water. It is strongly corrosive and very poisonous.

~Naphthalene and anthracene.~ These are hydrocarbons occurring along with benzene in coal tar. They are white solids, insoluble in water. The well-known _moth balls_ are made of naphthalene. Large quantities of naphthalene are used in the preparation of _indigo_, a dye formerly obtained from the indigo plant, but now largely prepared by laboratory methods. Similarly anthracene is used in the preparation of the dye _alizarin_, which was formerly obtained from the madder root.

THE ALKALOIDS

This term is applied to a group of compounds found in many plants and trees. They all contain nitrogen, and most of them are characterized by their power to combine with acids to form salts. This property is indicated by the name alkaloids, which signifies alkali-like. The salts are soluble in water, and on this account are more largely used than the free alkaloids, which are insoluble in water. Many of the alkaloids are used in medicine, some of the more important ones being given below.

~Quinine.~ This alkaloid occurs along with a number of others in the bark of certain trees which grow in districts in South America and also in Java and other tropical islands. It is a white solid, and its sulphate is used in medicine in the treatment of fevers.

~Morphine.~ When incisions are made in the unripe capsules of one of the varieties of the poppy plant, a milky juice exudes which soon thickens. This is removed and partially dried. The resulting substance is the ordinary _opium_ which contains a number of alkaloids, the principal one being morphine. This alkaloid is a white solid and is of great service in medicine.

Among the other alkaloids may be mentioned the following: _Nicotine_, a very poisonous liquid, the salts of which occur in the leaves of the tobacco plant; _cocaine_, a crystalline solid present in coca leaves and used in medicine as a local anæsthetic; _atropine_, a solid present in the berry of the deadly nightshade, and used in the treatment of diseases of the eye; _strychnine_, a white, intensely poisonous solid present in the seeds of the members of the _Strychnos_ family.

INDEX

Acetaldehyde 405

Acetic acid 406

Acetone 411

Acetylene 203
series 399

Acids 106
binary 113
characteristics 106
definition 107
dibasic 159
familiar 106
monobasic 159
nomenclature 113
organic 405
preparation 141
strength 111
ternary 113
undissociated 107

Acker furnace, 279

Agate 260

Air 83
a mechanical mixture 89
carbon dioxide in 87
changes in composition 87
liquid 91
nitrogen in 87
oxygen in 85
poisonous effects of exhaled 88
properties 90
quantitative analysis of 85
regarded as an element 83
standard for density 229
water vapor in 87

Alabaster 308

Alchemists 9

Alchemy 9

Alcohol, common 402
denatured 404
ethyl 402
methyl 402
wood 402

Alcohols 401

Aldehydes 405

Alizarin 418

Alkali 107, 274
family 274

Alkaline-earth family 300

Alkaloids 418

Allotropic forms 22

Alloys 252

Alum 333
ammonium 334
ammonium chrome 384
ammonium iron 352
baking powders 335
potassium 333
potassium chrome 384
potassium iron 352

Aluminates 332

Aluminium 327
bronze 330, 359
chloride 333
family 327
hydroxide 332
metallurgy 328
occurrence 327
oxide 331
preparation 328
properties 329
silicates 335
uses 330

Amalgam 362

Amethyst 260, 331

Ammonia 123
composition 127
preparation 123
properties 124
uses 125

Ammonium 126
acid carbonate 295
carbonate 295
chloride 294
compounds 294

Ammonium hydrosulphide 296
hydroxide 126
molybdate 388
oxalate 407
sulphate 295
sulphide 295
sulphide, yellow 296

Analysis 40

Anhydride 135
carbonic 206
chromic 387
nitric 135
nitrous 135
phosphoric 243
sulphuric 153

Anhydrite 288

Aniline 417

Anion 106

Anode 99

Anthracene 418

Antimony 250
acids 251
alloys 253
chloride 252
metallic properties 252
occurrence 251
oxides 251
preparation 251
properties 251
sulphides 251

Apatite 175, 239, 311

Aqua ammonia 124

Aqua regia 185

Aqueous tension 25

Argon 80

Arsenic 246
acids 250
antidote 250
Marsh's test 248
occurrence 246
oxides 249
preparation 246
properties 247
sulphides 250
white 249

Arsenopyrites 246

Arsine 247

Asbestos 321, 336

Atmosphere 83
constituents 83
function of constituents 84

Atomic hypothesis 61
theory 59
and laws of matter 63
and radium 314
weights, 65
accurate determination 231
and general properties 167
and specific heats 233
calculation of 231
Dalton's method 223
direct determination 233
from molecular weights 230
relation to equivalent 224
standard for 66
steps in determining 224

Atoms 62
size 65

Atropine 419

Aurates 396

Avogadro's hypothesis 226
and chemical calculations 235
and molecular weights 227

Azote 78

Azurite 357

Babbitt metal 253

Bacteria 85
decomposition of organic matter by 122
nitrifying 85

Baking powders 285, 408
alum 335
soda 285

Barium 312
chloride 313
nitrate 313
oxides 312
sulphate 313

Barytes 312

Bases 107
characteristics 107
definition 108
familiar 107
nomenclature 113
organic 412
strength 113
undissociated 108

Basic lining process 346

Bauxite 332

Beer 404

Benzene 417
derivatives 417
series 399

Benzine 400

Bessemer process 345

Bismuth 253
basic salts 255
chloride 253
nitrate 253
occurrence 253
oxides 254
preparation 253
salts, hydrolysis of 254
subnitrate 256
uses 253

Bismuthyl chloride 256

Blast furnace 341
lamp 38

Bleaching powder 306

Bleaching by chlorine 181
by sulphurous acid 152

Boiler scale 320

Bone ash 311

Bone black 200

Borax 265
bead 266

Bornite 357

Boron 257, 264
acids 265
fluoride 264
hydride 264
occurrence 264
oxides 264
preparation 264
properties 264

Brass 323

Bread making 416

Bromides 190

Bromine 187
occurrence 187
oxygen compounds 190
preparation 187
properties 188

Bronze 359
aluminium 330, 359

Butter fat 410

Butyric acid 407

By-product 284

Cadmium 325
compounds 326

Cæsium 294

Calamine 321

Calcite 305

Calcium 301
carbide 203, 310
carbonate 305
chloride 306
fluoride 308
hydroxide 303
occurrence 301
oxide 302
phosphate 246, 311
preparation 302
sulphate 308

Calomel 363

Calorie 76

Caramel 414

Carbohydrates 413

Carbolic acid 417

Carbon 196
allotropic forms 196
amorphous 198
compounds 196
crystalline forms 197
cycle in nature 88
dioxide 204
and bases 206
and plant life 88
in air 87
occurrence 204
preparation 204
properties 204
solid 204
disulphide 160, 210
family 196
hydrogen compounds 201
monoxide 208
occurrence 196
oxides 203
properties 200
pure 198
retort 199
uses 200

Carbonates 207
acid 207

Carbonic acid 206

Carborundum 259

Carnallite 288

Casein 414

Cassiterite 370

Catalysis 153

Catalyzers 153

Cathode 99

Cation 106

Caustic potash 288
soda 278

Celestite 312

Celluloid 415

Cellulose 415

Cement 304

Ceramic industries 336

Cerium 377

Chalcedony 260

Chalcocite 357

Chalcopyrite 357

Chalk 305

Chamber acid 157

Changes, physical and chemical 2

Charcoal 199

Chemical affinity 12
changes 2
compounds 7
equilibrium 128
properties 3

Chemistry, definition 4

Chili saltpeter 191, 285

Chinaware 336

Chloric acid 187

Chlorides 186

Chlorine 177
bleaching action 181
chemical properties 180
family 174
historical 177
occurrence 178
oxides 187
oxygen acids 187
preparation 178
properties 179

Chloroform 401

Chloroplatinic acid 393

Chlorous acid 187

Chromates 385

Chrome alum 384

Chromic acid 388
anhydride 387
chloride 383
hydroxide 383
sulphate 384
sulphide 384

Chromite 383

Chromium 383
a base-forming element 383
an acid-forming element 385
occurrence 383

Cinnabar 363

Citric acid 408

Clay 336

Coal 199
gas 217
products 400
tar 218

Cobalt 354
compounds 354

Cocaine 419

Coke 199

Collodion 415

Colemanite 265

Combining weights 225

Combustion 17
broad sense 20
in air 19
phlogiston theory 19
products 18
spontaneous 20
supporters 213

Compounds, chemical 7
isomeric 414
of metals, preparation 265
structure of 118

Conservation of energy 4
of matter 5

Contact process 154

Converter, Bessemer 345

Copper 357
acetate 407
alloys of 359
family 356
hydroxide 360
metallurgy 357
occurrence 357
ores 357
oxide 360
properties 358
refining 358
sulphate 361
sulphide 361
uses 359

Copperas 350

Coral 305

Corrosive sublimate 363

Corundum 331

Cream of tartar 408

Crocoisite 383

Cryolite 175, 328

Crystallization 98
water of 54, 75

Crystallography 161

Crystals 161
axes of 161
systems 162

Cupric compounds 360

Cuprite 360

Cuprous compounds 360
chloride 360
oxide 360

Cyanides 210
solutions are alkaline 210

Dalton's atomic hypothesis 61

Decay 21

Decomposition of organic matter 122

Decrepitation 55

Deliquescence 55

Density of gases 230

Desiccating agents 55

Developers 367

Dewar bulb 91

Dextrose 414

Diamond 197

Dichromates 385

Dichromic acid 385

Dimorphous substances 163

Dissociation 99
and boiling point 101
and freezing point 101
equations of 112
extent of 113

Distillation 50

Dogtooth spar 306

Dolomite 319

Double decomposition 71

Drummond light 38

Dyeing 333

Dynamite 409

Earth metals 327

Efflorescence 54

Electric furnace 221

Electro-chemical industries 269

Electrode 99

Electrolysis 99
of sodium chloride 102
of sodium sulphate 103
of water 41, 102

Electrolytes 99

Electrolytic dissociation 99

Electroplating 366

Electrotyping 359

Elements, definition 8
atomic weights 232
earlier classification 165
names 11
natural groups 165
number of 9
occurrence 10
periodic division 166
physical state 10
symbols of 11

Emery 331

Energy 4
and plant life 89
chemical 5
conservation of 4
transformation of 5

Enzyme 405

Epsom salts 320

Equations 68
are quantitative 72
knowledge requisite for 69
not algebraic 74
reading of 69

Equilibrium 138
chemical 138
in solution 139
point of 138

Equivalent 224
determination of 224
elements with more than one 225
relation to atomic weight 224

Etching 177

Ether 411

Ethereal salts 409

Ethers 411

Ethylamine 412

Ethylene series 399

Eudiometer 43

Evaporation 11

Families in periodic groups 170
triads 165

Family resemblances 170

Fats 409

Fatty acid series 405

Feldspar 261, 335

Fermentation 404
acetic 406
alcoholic 404, 405
lactic 414

Ferric chloride 352
hydroxide 352
salts 351
reduction 353
sulphate 352

Ferrochromium, 383

Ferromanganese 343

Ferrosilicon 259

Ferrous carbonate 351
salts 350
oxidation of 353
sulphate 350
sulphide 350

Fertilizers 245

Filtration 6, 51
beds 52

Fire damp 202

Flames 213
appearance 214
blowpipe 216
Bunsen 214
conditions for 213
hydrogen 34
luminosity 216
oxidizing 214
oxyhydrogen 37
reactions 296
reducing 214
structure 214

Flash lights 317

Flint 260

Fluorides 177

Fluorine 175

Fluorspar 175, 308

Fluosilicic acid 259

Flux 340

Fool's gold 351

Formaldehyde 405

Formalin 405

Formic acid 406

Formulas 68
how determined 234
structural 119

Fractional distillation 51

Franklinite 321

Fuels 220

Furnace, arc 221
electric 221
resistance 221

Fusion methods 271

Galena 373

Gallium 327

Galvanized iron 323

Gas, collection of 15
coal 217
fuel 217
illuminating 217
measurement of 23
natural 219
purification of 218
water 219

Gases, table 220

Gasoline 400

German silver 323, 359

Germanium 370

Germs, effect of cold on 53
in air 84
in water 52

Glass 262
coloring of 263
etching of 177
molding of 263
nature of 263
varieties 263

Glauber's salt 281

Glazing 336

Glucose 414

Glycerin 405
nitrates of 409

Gold 393
alloys 396
chloride 396
coin 359
extraction of 394
in copper 358
mining 394
occurrence 393
properties 396
refining of 395
telluride 394

Goldschmidt method 269, 330

Gram-molecular weight 236

Granite 336

Graphite 198

Gun cotton 415
metal 359
powder 292

Gypsite 308

Gypsum 308

Halogens 174

Hard water 309

Heat of reaction 75

Helium 80, 314

Hematite 339, 349

Homologous series 398

Hydriodic acid 193

Hydrobromic acid 189

Hydrocarbons 201, 398
properties 400
series 398
substitution products 401

Hydrochloric acid 182
composition 183
oxidation of 185
preparation 182
properties 184
salts 186

Hydrocyanic acid 210

Hydrofluoric acid 176
etching by 177
salts of 177

Hydrogen 28
dioxide 56
explosive with oxygen 35
occurrence 28
preparation from acids 30
preparation from water 28
properties 32
standard for atomic weights 66
standard for molecular weights 227
sulphide 146
uses 38

Hydrolysis 254
conditions affecting 255
partial 255

Hydrosulphuric acid 146

Hydroxyl radical 112

Hypochlorous acid 187

Hypothesis 61
Avogadro's 226
Dalton's 61

Ice manufacture 125

Iceland spar 305

Indigo 418

Indium 327

Insoluble compounds 272

Iodic acid 194

Iodides 193

Iodine 190
oxygen compounds 193
preparation 191
properties 192
tincture 192

Iodoform 192, 401

Ions 100
and electrolytes 104

Iridium 393

Iron 339
alum 352
cast 343
compounds 349
cyanides 352
disulphide 351
family 338
metallurgy 339
occurrence 339
ores 339
oxides 349
pure 348
varieties 342, 347
wrought 343

Jasper 260

Kainite 288

Kaolin 261, 335

Kerosene 400

Ketones 411

Kieserite 288

Kindling temperature 17

Krypton 80

Lactic acid 408

Lampblack 200

Laughing gas 132

Law, definition 61
of Boyle 24
of Charles 23
of combining volumes 194
of conservation of energy 4
of conservation of matter 5, 59
of definite composition 59
of Dulong and Petit 233
of Gay-Lussac 194
of multiple proportion 60
of Raoult 233
periodic 169

Lead 373
acetate 375, 407
alloys 375
basic carbonate 376
carbonate 376
chloride 377
chromate 377
insoluble compounds 376
metallurgy 373
nitrate 375
occurrence 373
oxides 375
peroxide 375
properties 374
red 375
soluble salts 375
sugar of 375
sulphate 377
sulphide 377
white 376

Le Blanc soda process 282

Levulose 415

Lime 302
air-slaked 303
hypochlorite 307
kilns 303
slaked 303

Lime light 38

Limestone 305

Limewater 303

Limonite 339

Litharge 375

Lithium 294

Luminosity of flames 216

Lunar caustic 366

Magnesia 318
alba 319
usta 318

Magnesite 318

Magnesium 317
basic carbonate 319
carbonate 318
cement 318
chloride 319
family 316
hydroxide 318
oxide 318
silicates 321
sulphate 320

Magnetite 339, 349

Malachite 357

Manganates 381

Manganese 379
a base-forming element 380
an acid-forming element 381
in glass 263
occurrence 379
oxides 380

Manganic acid 381

Manganous salts 380

Marble 305

Marl 305

Marsh gas 202

Matches 242

Matte 358

Matter, classification 6
conservation 5
definition 5
kinds 9

Measurement of gases 23

Mechanical mixtures 6

Meerschaum 321, 336

Mercuric chloride 363
iodide 364
oxide 14, 362
sulphide 363

Mercurous chloride 363

Mercury 361
iodides 364
metallurgy 361
occurrence 361
oxides 362
uses 362

Metaboric acid 265

Metallurgy 268

Metals 165, 267
action on salts 271
definition 267
extraction 268
occurrence 267
preparation of compounds 269
reduction from ores 268

Metaphosphoric acid 245

Metarsenic acid 250

Metasilicic acid 261

Metastannic acid 371

Methane 202, 399

Methylamine 412

Mexican onyx 305

Mica 261, 336

Microcosmic salt 244

Milk 414

Minerals 267

Minium 375

Mixed salts 244

Molasses 413

Molecular weights 226
boiling-point method 233
compared with oxygen 228
determination 226
freezing-point method 233
oxygen standard 227
of elements 232
vapor-density method 229

Molecule 62

Molybdenum 388

Molybdic acid 388

Monazite sand 377

Mordants 333

Morphine 418

Mortar 304

Moth balls 418

Muriatic acid 182

Naphthalene 418

Naphthas 400

Nascent state 182

Natural gas 219
sciences 1

Neon 80

Neutralization 108
a definite act 109
definition 109
heat of 109
partial 111

Niagara Falls 269, 329

Nickel 354
coin 359
compounds 354
plating 354

Nicotine 419

Nitrates 131

Nitric acid, 128
action on metals 130
decomposition 129
oxidizing action 130
preparation 128, 140
properties 129
salts 131

Nitric oxide 133

Nitrites 132

Nitrobenzene 417

Nitrocellulose 415

Nitrogen 78
compounds 122
in air 87
occurrence 78, 122
oxides 132
preparation 78
properties 80

Nitroglycerin 409

Nitrosulphuric acid 155

Nitrous acid 132
oxide 132

Non-metals 165

Oil of myrbane 417
of vitriol 154

Oleic acid 408

Olein 409

Oleomargarine 410

Onyx 260

Opal 260

Open-hearth process 346

Opium 418

Ores 267

Organic bases 412
chemistry 201, 397
matter, decomposition 122

Orpiment 246

Orthoarsenic acid 250

Orthophosphates 244

Orthophosphoric acid 244

Orthosilicic acid 261

Osmic acid 393

Osmium 393
tetroxide 393

Oxalic acid 407

Oxidation 17, 353
definition 18

Oxidizing agent 37

Oxygen 13
and ozone 22
commercial preparation 16
history 13
importance 21
in air estimation, 85
in air function, 84
occurrence 13
preparation 13
properties 16
standard for atomic weights 66
two atoms in molecule 227

Oxyhydrogen blowpipe 37

Ozone 21, 137

Palladium 390

Palmitic acid 407

Palmitin 409

Paraffin 400

Paris green 250

Parkes's method for silver 364

Pearls 305

Perchloric acid 187

Periodic acid 194

Periodic division 166
groups 167
law 169
law, imperfections 172
law, value 171
table 168
table, arrangement 166

Permanent hardness 310

Permanganates 381

Permanganic acid 381

Peroxides 278

Petroleum 399

Pewter 372

Phenol 417

Philosopher's stone 9

Phlogiston 19

Phosphates 245

Phosphine 242

Phosphonium compounds 243

Phosphoric acid 244

Phosphorite 239

Phosphorous acid 244

Phosphorus 239
acids 243
family 238
hydrogen compounds 242
occurrence 239
oxides 243
preparation 239
properties 240
red 241
yellow 240

Photography 367

Physical changes 2
properties 3
properties and periodic groups 171
state 3

Physics 1, 4

Pitchblende 314

Plaster of Paris 308

Platinic chloride 393

Platinized asbestos 391

Platinous chloride 393

Platinum 391
a catalytic agent 152, 392

Pneumatic trough 16

Polyboric acid 265

Polyhalite 288

Polysilicic acids 261

Porcelain 336

Portland cement 304

Potash 293

Potassium 287
acid carbonate 294
acid sulphate 294
acid sulphite 294
alum, aluminium 334
alum, chrome 384
alum, iron 352
and plant life 287
aurate 396
bromide 290
carbonate 293
chlorate 291
chloride 290
chromate 385
cyanide 293
dichromate 386
ferricyanide 352
ferrocyanide 352
hydroxide 288
hydroxide, action of halogens 289
hypochlorite 289
iodide 290
manganate 381
nitrate 291
occurrence 287
permanganate 381
preparation 288
sulphate 294

Precipitated chalk 306

Precipitation 140

Properties, chemical 3
physical 3

Prussic acid 210

Puddling 343
furnace 344

Pyridine 412

Pyrites 351

Pyrolusite 380

Pyrophosphoric acid 245

Quantitative equations 72

Quartz 260

Quicklime 302

Quinine 418

Quinoline 412

Radical 112

Radium 313

Reaction, classes 70
addition 70
completed 139
heat of 75
of decomposition 70
of double decomposition 71
of substitution 70
reversible 137
steps in 131

Realgar 246

Red lead 375
phosphorus 241

Reducing agent 37

Reduction 36, 354

Rennin 414

Resemblances, family 170

Respiration 87

Rhodium 390

Rochelle salts 408

Rouge 349

Rubidium 294

Ruby 331

Ruthenium 390

Rutile 264

Safety lamp 202

Sal ammoniac 294
soda 282

Salt 280

Saltpeter 291
Chili 285

Salts, 109
acid, 112

Salts basic 111
binary 114
characteristics 109
definition 109
insoluble 272
mixed 244
nomenclature 113
normal 112
preparation by precipitation 270

Sand 260

Sandstone 260

Saponification 410

Sapphire 331

Satinspar 308

Scale 320

Schönite 288

Selenite 308

Selenium 161

Serpentine 320, 336

Shot 247, 375

Siderite 339

Silica 260

Silicates 261

Silicic acids 261

Silicides 259

Silicon 258
acids 261
dioxide 260
fluoride 258
hydride 258

Silver 364
amalgamation process 364
bromide 367
chloride 367
coin 359
German 359
in copper ores 358
iodide 367
metallurgy 364
nitrate 366
oxide 366
parting of 365
refining 365
sulphide 366

Slag 340

Smalt 355

Smithsonite 321

Smokeless powder 293

Soaps 410

Soda ash 284

Soda lime 202

Sodium 276
acetate 407
bicarbonate 285
carbonate 282
carbonate, historical 284
chloride 280
chromates 386
hydrogen carbonate 285
hydroxide 278
hyposulphite 282
iodate 191
nitrate 285
occurrence 276
peroxide 277
phosphates 286
preparation 276
properties 277
sulphate 281
sulphite 281
tetraborate 287
thiosulphate 282

Solder 372, 375

Solubility of gases 95
of solids 96

Solution 94
and chemical action 53
boiling point 98
classes 94
distribution of solids in 98
electrolysis of 99
freezing point 99
of gases in liquids 94
of solids in liquids 96
properties 98
saturated 97
supersaturated 98

Solvay soda process 283

Sombrerite 239

Spectroscope 296

Sphalerite 325

Spiegel iron 343

Spinel 332

Spontaneous combustion 20

Stalactites 305

Stalagmites 305

Standard conditions 23

Stannates 372

Stannic acid 372
chloride 372
oxide 372

Stannous chloride 372

Starch 415

Stassfurt salts 287

Stearic acid 407

Stearin 409

Steel 345
alloys 348
properties 347
tempering of 348
tool 347

Stibine 251

Stibnite 250

Stoneware 336

Strontianite 312

Strontium 312
hydroxide 312
nitrate 312

Structural formulas 119

Structure of compounds 119

Strychnine 419

Substitution 70

Sugars 412
cane 412
fruit 415
grape 414
milk 414

Sulphates 159

Sulphides 148

Sulphites 152
action of acids on 150

Sulphur 143
allotropic forms 144
chemical properties 145
comparison with oxygen 161
dioxide 149
preparation 149
properties 150
extraction 143
flowers of 143
occurrence 143
oxides 149
physical properties 144
trioxide 152
uses 146
varieties 144

Sulphuric acid 154
action as an acid 157
action on metals 157
action on organic matter 158
action on salts 158
action on water 158
fuming 155
manufacture 154
oxidizing action 157
plant 156
properties 157
salts 159

Sulphuric anhydride 153

Sulphurous acid 151

Superphosphate of lime 246

Sylvine 288

Symbols 11

Synthesis 40

Table, alkali metals 274
alkaline-earth metals 300
alloys of copper 359
aqueous tension Appendix B
atomic weights Appendix A
chlorine family 174
composition of earth's crust 10
composition of fuel gases 220
constants of elements Appendix B
copper family 356
elements Appendix A
gold and platinum metals 390
hydrocarbons 399
magnesium family 316
manganese and chromium 379
periodic arrangement 168
phosphorus family 238
silicon family 257
solubility of gases in water 95
solubility of salts 96
solubility of salts at different temperatures 97
tin and lead 370
weights of gases Appendix B

Talc 321, 336

Tartar emetic 408

Tartaric acid 408

Tellurium 161

Temporary hardness 309

Ternary acids 113
salts 114

Tetraboric acid 265

Thallium 327

Theory, atomic 61
definition 64
value of 64

Thermite 331

Thio compounds 282

Thiosulphates 159

Thiosulphuric acid 159

Thorium 377

Tin 370
block 371
compounds 372
crystals 372
family 370
foil 371
metallurgy 370
plate 371
properties 371
uses 371

Titanium 257, 264

Topaz 331

Triad families 166

Tungsten 388

Type metal 253, 375

Uranium 388

Valence 116
a numerical property 116
and combining ratios 118
and equations 120
and formulas 120
and periodic groups 162
and structure 118
definition 116
indirectly determined 117
measure of 117
variable 117

Vaseline 400

Venetian red 349

Verdigris 407

Vermilion 363

Vinegar 406

Vitriol, blue 361
green 350
oil of 154
white 324

Volume and aqueous tension 25
and pressure 24
and temperature 23
of combining gases 194

Water 40
a compound 40
and disease 49
catalytic action of 154
chalybeate 351
chemical properties 53
composition 47
composition by volume 44
composition by weight 47
dissociation of 210
distillation of 50
electrolysis of 41, 103
filtration of 51
gas 219
hard 309
historical 40
impurities in 48
in air 87
mineral 49
occurrence 48
of crystallization 54, 75
physical properties 53
purification of 50
qualitative analysis 41
quantitative analysis 42
river 49
sanitary analysis 50
self-purification 53
softening of 310
standard substance 55
synthesis 43
uses of 55

Weights, atomic 65

Welsbach mantles 219, 377

Whisky 404

Wine 404

Witherite 312

Wood alcohol 402
distillation 402

Wood's metal 254

Xenon 80

Yeast 403

Zinc 321
alloys of 323
blende 321
chloride 325
flowers of 322
metallurgy 321
occurrence 321
oxide 324
sulphate 324
sulphide 325
white 324

Zymase, 403

ANNOUNCEMENTS

AN ELEMENTARY STUDY OF CHEMISTRY

By WILLIAM McPHERSON, Professor of Chemistry in Ohio State University, and WILLIAM E. HENDERSON, Associate Professor of Chemistry in Ohio State University.

12mo. Cloth. 434 pages. Illustrated. List price, $1.25; mailing price, $1.40

This book is the outgrowth of many years of experience in the teaching of elementary chemistry. In its preparation the authors have steadfastly kept in mind the limitations of the student to whom chemistry is a new science. They have endeavored to present the subject in a clear, well-graded way, passing in a natural and logical manner from principles which are readily understood to those which are more difficult to grasp. The language is simple and as free as possible from unusual and technical phrases. Those which are unavoidable are carefully defined. The outline is made very plain, and the paragraphing is designed to be of real assistance to the student in his reading.

The book is in no way radical, either in the subject-matter selected or in the method of treatment. At the same time it is in thorough harmony with the most recent developments in chemistry, both in respect to theory and discovery. Great care has been taken in the theoretical portions to make the treatment simple and well within the reach of the ability of an elementary student. The most recent discoveries have been touched upon where they come within the scope of an elementary text. Especial attention has been given to the practical applications of chemistry, and to the description of the manufacturing processes in use at the present time.

EXERCISES IN CHEMISTRY. By WILLIAM McPHERSON and WILLIAM E. HENDERSON. (_In press._)

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A FIRST COURSE IN PHYSICS

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This one-year course in physics has grown out of the experience of the authors in developing the work in physics at the School of Education of The University of Chicago, and in dealing with the physics instruction in affiliated high schools and academies.

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