Chapter C: W. HEATON, F.I.C., F.C.S., Lecturer on Chemistry at the (5)

In addition to the gases and vapours already enumerated, as well as others which exist in minute quantity, or which are of only occasional occurrence, Pasteur and other investigators have discovered in the air living germs which are capable of exciting putrefaction and fermentation, and which are competent, in some instances, to engender disease when they are injected into the blood of animals. In fact, the spread of infectious diseases, _e.g._, smallpox, typhus fever, cattle plague, &c., is attributed to the presence in the atmosphere of the germs of such maladies. These germs are believed to be living beings, which develope and multiply at the expense of the tissues of the larger animals into whose systems they have found entrance.

=Air, Vitiated.= As has been stated in the previous article, the air consists chiefly of two gases, oxygen and nitrogen. In all open places it has a similar composition, as might be concluded from the constant mingling which takes place by the agency of currents continually in movement, although sometimes to an inconsiderable extent only. Dr Angus Smith regards air as very pure when it contains not less than 20·99 per cent. by volume of oxygen, and 0·030 of carbonic anhydride (acid). According as the proportion of the former gas diminishes and that of the latter increases beyond certain limits in the air by which we are surrounded, it becomes more or less deteriorated and unfit to be breathed, particularly as the increased amount of carbonic acid is, in crowded dwellings, assembly rooms, theatres, and confined inhabited spaces, associated with deleterious and putrescent exhalations from the person.

_The following tables exhibit the amount of carbonic
acid in close places in London._

Per-centage
=I.= by volume.
Chancery Court, closed doors, 7 feet from the ground,
March 3 ·193
Same, 3 feet from ground ·203
Chancery Court, doors wide open, 4 feet from ground,
11·40, March 5 ·0507
Same, 12·40 p.m., 5 feet from ground ·045
Strand Theatre, gallery, 10 p.m. ·101
Surrey Theatre, boxes, March 7, 10·30 p.m. ·218
Olympic, 11·30 p.m. ·0817
Same, 11·55 p.m. ·1014
Victoria Theatre, boxes, March 24, 10 p.m. ·126
Haymarket Theatre, dress circle, March 18, 11·30 p.m. ·0757
Queen's Ward, St. Thomas's Hospital, 3·25 p.m. ·052
Edward's Ward, St. Thomas's Hospital, 3·30 p.m. ·052
Victoria Theatre, boxes, April 4. ·076
Effingham, 10·30 p.m., April 9, Whitechapel ·126
Pavilion, 10·11 p.m., April 9, Whitechapel ·152
City of London Theatre, pit, 11·15 p.m., April 16 ·252
Standard Theatre, pit, 11 p.m., April 16 ·320

Dr Angus Smith states that out of 339 specimens of air obtained from various mines he found 35 normal or nearly so, 81 decidedly impure, and 212 exceedingly bad; he also adds that owing to the frequent firing of charges of gunpowder within the mines, and from other causes, the atmosphere is further contaminated with sulphuretted hydrogen, sulphate, carbonate, sulphide, sulphocyanide of potassium, and nitrate of potassium, carbon, sulphur, carbonate of ammonia, organic matter, sand, and sulphurous and arsenious acids.

The air of large cities, which are the seats of manufacturing industry, is always more or less charged with the exhalations given off by chemical and other works. The sulphuric-acid works contribute sulphuric, sulphurous, nitrous, and arsenious acids; copper works, in which pyrites is employed, give off large quantities of sulphurous acid, mixed with arsenic and a little copper; manure works, in many cases, send out compounds of fluorine, besides sulphuric acid; glass works, sulphuric and hydrochloric acids; and alkali works, hydrochloric acid (although in small quantities), which very frequently contains arsenic. Of ammonia, Angus Smith remarks: "It is one measure of the 'sewage' of the air; it is the result of decomposition. It is not, in these small quantities, hurtful, so far as we know. The ammonia is in no case free, but combined probably with hydrosulphuric, hydrochloric, and sulphuric acid in towns. In country places it is, at all events partly, united to carbonic acid.

II. _London Air.--Carbonic Acid, Metropolitan Railway,
November, 1869._

+--------+----------------------------+------------+---------+---------+
| | | |Carbonic | Oxygen, |
| Date. | Place. |Time of Day.| Acid, |per cent.|
| | | |per cent.| |
+--------+----------------------------+------------+---------+---------+
| 1869. |Tunnel between Gower Street | | | |
|Nov. 12.|and King's Cross Stations; | 10 a.m. | ·150 | 20·60 |
| |specimen taken at the open | | | |
| |window, first-class | | | |
| |carriage. | | | |
| | | | | |
| " 12.|Tunnel between Gower Street | | | |
| |and King's Cross Stations; | 7·30 p.m. | ·078 | 20·79 |
| |specimen taken at the open | | | |
| |window, first-class | | | |
| |carriage. | | | |
| | | | | |
| " 12.|Tunnel Praed Street; | | | |
| |specimen taken at the open | 10·30 a.m. | ... | 20·71 |
| |window, first-class | | | |
| |carriage. | | | |
| | | | | |
| " 15.|Specimen taken during | | | |
| |journey between Gower Street| 10·15 a.m. | ·338 | 20·66 |
| |and King's Cross, | | | |
| |first-class carriage, window| | | |
| |open. | | | |
| | | | | |
| " 15.|Same | 3 p.m. | ·155 | 20·70 |
| | | | | |
| " 15.|Same | 11 p.m. | ·150 | 20·74 |
| | | | | |
+--------+----------------------------+------------+---------+---------+
| |Average | | ·1452 | 20·70 |
+--------+----------------------------+------------+---------+---------+
ANGUS SMITH.

_The Air of Mines_ (_Metalliferous_).

+-------------+---------------------+-------+-------+-------+--------+
|Name of Mine,|Description of place,|Thermo-|Number |Oxygen,|Carbonic|
|and depth |where taken and time |meter, |of Men | per | Acid, |
|from surface,|when taken. |Fahr. |working| cent. | per |
|in fathoms. | | |in it. | | cent. |
+-------------+---------------------+-------+-------+-------+--------+
| | | | | | |
| Hurst |End, 300 ft. beyond | ... | 2 | ... | 1·99 |
| |a rise, 9 ft. high, | | | | |
| |7 ft. wide. | | | | |
| | | | | | |
| Old Gang |End of level | ... | 2 | 20·58 | ·48 |
| | | | | | |
| " |End of level | ... | 2 | ... | ·28 |
| | | | | | |
| " |(_a_) Rise 7 ft. | ... | 2 | 20·25 | ·39 |
| |high, 132 ft. from | | | | |
| |current. | | | | |
| | | | | | |
| Grassington |(_b_) End of cross | ... | 2 | 20·94 | ·06 |
| |cut, 480 ft. from | | | | |
| |rise. | | | | |
| | | | | | |
| " |End, 480 ft. from | ... | 2 | 19·53 | 1·59 |
| |rise. | | | | |
| | | | | | |
| " |Rise 60 ft. high in | ... | 2 | 19·52 | 1·72 |
| |shale. | | | | |
| | | | | | |
| " |End, 60 ft. from | ... | 2 | 20·47 | 1·06 |
| |rise. | | | | |
| | | | | | |
| " |(_c_)End, 840 ft. | ... | 2 | 20·08 | ·94 |
| |from rise. | | | | |
+-------------+---------------------+-------+-------+-------+--------+
(_a_) Air machine.
(_b_) Unusual amount of dust.
(_c_) Crystals were chiefly hexagons.
ANGUS SMITH.

The following table, showing the amount of ammonia present in rain collected at the different places named, is from Dr Smith's work, 'Air and Rain.'

COMPARATIVE. AMMONIA.

That of Valentia (Ireland) taken as 1 or 100.

Ireland, Valentia ·1
Scotland, sea-coast, country places, west 2·69
Scotland, inland, country places, west 2·96
Scotland, sea-coast, country places, average 4·10
Scotland, sea-coast, country places, east 5·51
England, inland, country places, east 5·94
England, sea-coast, country places, west 10·55
German specimens 10·61
London, 1869 19·17
Scotland, towns (Glasgow not included) 21·22
St. Helen's 25·33
Runcorn 25·72
England, towns 28·67
Liverpool 29·89
Manchester, 1869 35·33
Manchester, 1869 and 1870, average 35·94
Manchester, 1870 36·54
Glasgow 50·55

The effects resulting from breathing an impure atmosphere are necessarily dependent upon the extent of the pollution and other conditions. When the contamination is moderate the first effect is headache, accompanied with lassitude, and a general paleness of the face and skin, owing to a diminution of the red corpuscles of the blood or to their imperfect aëration; the pulse becomes lowered, and at the same time the breathing is accelerated. When in addition to breathing such air from day to day is superadded the misfortune of an insufficiency of food, scrofula and consumption very often follow. Dr Guy has demonstrated the great mortality that is caused by consumption in those trades in which workmen pursue their calling in hot, close, gas-lit rooms, in comparison with those who pass most of their time in the open air. The amount of air required by each person in a room is no less than 2100 feet per hour; when the ventilation does not supply this amount of fresh air, the apartment smells stuffy, the furniture becomes coated with a film of organic matter, unless constantly cleaned, and the carbonic acid becomes increased beyond its normal quantity.

Dr Parkes has shown that bronchitis and consumption are more frequently than not contracted by those who live in an atmosphere of foul air. In the years 1834 to 1847 the proportion of deaths in the ill-ventilated prison of Leopoldstadt in Vienna was 86 per 1000, out of which number 51·4 per 1000 was due to phthisis or consumption; while in the well-ventilated House of Correction in the same city the deaths were 14 per 1000, of which 7·9 were from phthisis; hence 43·5 cases per 1000 of the deaths were clearly traceable to foul air and nothing else.

Mr Noel Hartley, in his valuable little manual, 'Water, Air, and Disinfectants,' says: "During the outbreak of cattle plague in 1866, in sheds containing twenty to thirty cows--which the owners kept closed to such an extent that all chinks in the doors and windows were stuffed with straw and matting, under an ignorant belief that thus the plague could be kept out--very frequently the entire stock died in two or three days after the first appearance of disease; while in other cases where animals were housed in a well-cleaned and tidily-kept shed, with a plentiful supply of fresh air, not only did some of them escape the disease altogether, but the deaths were reduced to one third of the number of beasts attacked."

The large supply of fresh air necessary in hospitals for contagious diseases is fully recognised by medical men, and more especially so in America. Wounds carefully protected from contact with impure air do not suppurate, and organic fluids do not putrefy. On the other hand, in a bad atmosphere sores become unhealthy, and are difficult to heal, erysipelas and hospital gangrene frequently set in, while the best prevention and the best means of cure for such afflictions is the greatest possible exposure to fresh air.

Vitiated air, as a consequence of over-crowding, aids the spread of measles, scarlet fever, and the much to be dreaded smallpox; it brings on ophthalmia, a troublesome inflammation of the eyes, and is not unfrequently the cause of the ricketty and scrofulous condition of children. Although exposure to cold does cause such affections as bronchitis, pneumonia, cold in the head, sore throat, and other affections of the respiratory organs, it is more frequently the case that they are the result of a sudden change of temperature, such as experienced in coming out of a crowded assembly in a close, badly-ventilated building, than by actually cold weather. This is decidedly and strikingly shown by the fact which Dr de Chaumont has quoted, that the British Army when in the Crimea, when lodged in tents during extremely rigorous weather, experienced a wonderful condition of health, such a thing as a cold being an unknown complaint; but when some of the men were placed in huts which were much warmer, and into which there was a smaller circulation of fresh air, the sick rate increased, and coughs and colds began to put in an appearance. Persons who during summer and winter sleep with their windows more or less open cannot endure a night spent in the chamber with the chimney closed and the window shut. A less refreshing sleep occupies the night, and a somewhat feverish sensation is felt next morning.

If in cold weather the window be opened only one inch at the top, the difference in the air in the bedroom is something quite beyond comprehension to those who have not paid attention to these things. See VENTILATION.

=Air, Analysis of.= Priestley's discovery of oxygen gas in 1774 prepared the way for the knowledge of the real composition of air, which was discovered about the same time by Scheele and Lavoisier. Scheele's method of operating was by exposing some atmospheric air to a solution of sulphide of potassium. Lavoisier effected the same object by the combustion of iron wire and phosphorus, and subsequently by heating mercury on a flask filled with air for some time, just below its boiling point.

These, however, were but elementary methods, which, however creditable to the ingenuity of the great founders of modern chemistry, not only failed in accuracy, but took no account of the presence and amount of two most important constituents in the atmosphere, viz. carbonic anhydride (acid) and ammonia.

_Determination of Aqueous Vapour._ To effect this an aspirator must be used (see ASPIRATOR). This instrument is easily made, and is not expensive. The accompanying figure will illustrate the arrangement generally adopted: _a_ is an aspirator made of galvanised iron or sheet zinc. It holds from 50 to 200 litres (from 11 to 44 gallons). By this means a known volume of air is drawn through the tubes marked _b_, _c_, _d_, _e_, which may be filled with pumice-stone moistened with strong sulphuric acid; but if the carbonic acid is to be estimated as well, _b_ and _c_ are filled with moist hydrate of lime (potash used to be employed, but hydrate of lime is to be preferred, as the potash absorbs oxygen), and _d_ and _e_ as above. Each of the tubes is accurately weighed previously to connecting them with the apparatus.

It is imperative to have each of the tubes connected by perfectly air-tight joints. The gain of weight in _d_ and _e_ gives the water in _b_ and _c_ the carbonic acid.

_Determination of Carbonic Acid._ A better and perhaps more exact means of determining the carbonic acid is that invented by PETTENKOFER. It may be briefly described as follows:--Baryta water of definite strength is prepared and accurately standardised by a standard solution of oxalic acid. A portion of this baryta water is then made to act upon a definite quantity of air. It will absorb the whole of the carbonic acid in that air.

The alkalinity of the liquid will in consequence be diminished; it will take less of the oxalic-acid solution than before, which shows so much less caustic baryta, and from which the carbonic acid absorbed may be easily calculated.

_The actual Analysis._ Two kinds of baryta water may be used, the one containing 7 grammes to the litre, the other three times that strength; 1 c. c. of the stronger = 3 m. grms. of carbonic acid; 1 c. c. of the weaker = 1 m. grm. The baryta water is best kept in the bottle represented below.

The bottle (_a_) contains the baryta water. It has an accurately-fitting double-perforated stoppered caoutchouc. The left-hand tube is connected with the tube (_b_) containing pumice-stone moistened with potash, while the right-hand one is a syphon. When required for use the stop-cock (_f_) is opened, and suction applied by a glass tube to F. The syphon is thus filled and the stop-cock closed. If a pipette is required to be filled its nozzle is inserted at F, the stop-cock compressed, and the fluid immediately rises into the pipette.

The air entering the bottle as the fluid decreases in _a_ is, of course, thoroughly deprived of its carbonic acid by the tubes at _b_.

The first thing to be done is to standardise the baryta solution by a solution of oxalic acid, containing 2·8636 grammes of crystallised oxalic acid to the litre.

Thirty c. c. of baryta solution are run into a small flask, and the oxalic acid run in from a Mohr's burette with float, the vanishing-point of the alkaline reaction being ascertained by delicate turmeric paper. As soon as a drop placed on turmeric paper does not give a brown ring the end is attained.

The actual analysis is performed by filling a bottle of known capacity, with the aid of a pair of bellows, with the air to be analysed, then distributing over its sides 45 c. c. of the baryta water it is left for half an hour. The turbid water is poured into a cylinder, closely secured, and allowed to deposit; then take out 30 c. c. by a pipette of the clear fluid, run in the solution of oxalic acid, multiply the volume used by 1·5, and deduct the produce from the c. c. of oxalic acid used for 45 c. c. of the fresh baryta water. A different method has been suggested by Dr Angus Smith, viz. to measure the carbonic anhydride by the turbidities of the baryta water; this is, in fact, a colorimetric test. For rough approximative results Dr Smith's process will be found a very useful and convenient one. It depends upon the fact that the amount of carbonic acid in a given quantity of air will not produce a precipitate in a given quantity of lime or baryta water unless the carbonic acid is in excess. The following is one of his tables:--Columns 1 and 2 give the rates of carbonic acid in the quantity of air which will produce no precipitate in half an ounce of lime water. Column 3 is the same as column 2; but 14·16 c. c. (half an ounce) is added to give the corresponding size of the bottle, and column 4 gives the size of the bottle in ounces.

To be used when the point of observation is "no
precipitate." Half an ounce of baryta water contains
about ·08 gramme of baryta.

Air at 0° C. and 760 millims. Bar.

Carbonic Acid Volume of Size of bottle Size of bottle
in the Air, Air in cubic in cubic in ounces
per cent. centimètres. centimètres. Avoirdupois.

·03 185 199 7·06
·04 139 154 5·42
·05 111 125 4·44
·06 93 107 3·78
·07 79 93 3·31
·08 70 84 2·96
·09 62 76 2·69
·10 56 70 2·46
·11 51 65 2·29
·12 46 60 2·14
·13 43 57 2·01
·14 40 54 1·90
·15 37 51 1·81
·20 28 42 1·48
·25 22 36 1·29
·30 19 33 1·16
·40 14 28 1·04
·50 11 25 ·89
·60 9 23 ·89
·70 8 22 ·78
·80 6 20 ·72
1·00 5·5 19·7 ·70

Mr Wanklyn's process for the determination of carbonic acid in the atmosphere is as follows:--A solution of carbonate of soda is first made as follows: 4·47 grammes of gently-ignited carbonate of soda are dissolved in one litre of water, giving a solution of such a strength that 1 c. c. contains exactly 1 c. c. of carbonic acid (= 1·97 milligrammes of CO_{2}); a large quantity of baryta water (strength about 0·1 per cent.) is prepared.

If now 100 c. c. of clear baryta water be treated with 1 c. c. of carbonate of soda, just described, a certain degree of turbidity is produced.

If 2 c. c. of the solution be taken another degree of turbidity is produced, and so on. If, then, a bottle capable of holding 2000 c. c. of air, together with 100 c. c. of baryta water, be filled with the sample of air to be tested, there will be a certain depth of turbidity produced by shaking it up. Having got the air to expend itself on 100 c. c. of baryta water the degree is to be found by comparison with another 100 c. c. of baryta water, in which a like turbidity has been induced by means of the standard solution of carbonate.

Every c. c. of soda solution counts for a c. c. of carbonic acid in two litres of air. A consumption of 1 c. c. will correspond to ·05 volumes of carbonic acid per cent. Good air should accordingly not take more than 1 c. c. of soda solution, air which takes already 2 c. c. being already bad.

In order practically to carry out this method of estimating carbonic acid the following apparatus is required:--Several bottles capable of holding 2·210 c. c., and well stoppered (failing bottles of exactly the right capacity Winchester quart bottles will answer); a small pair of bellows; several colourless glass cylinders marked at 100 c. c. capacity--the Nesslerising cylinders will answer for this purpose--a graduated pipette or burette to deliver tenths of a c. c. of solution, the standard solution of carbonate of soda, and the baryta water, which may be of moderate strength.

The testing is managed thus: Winchester quart bottles having been made clean are rinsed with distilled water, and allowed to drain a little. They are then closed with their stoppers, and are ready for use. The operator having provided himself with two or three of these bottles and a small pair of bellows enters the room the air of which is to be tested. The stopper is then removed from one of the bottles, and some air of the room blown through with the bellows, and then the stopper is replaced, and the bottle carried away to be tested.

The testing is done by pouring into the bottle 100 c. c. of clear baryta water, shaking up for two or three minutes, and then pouring out into a cylinder of colourless glass, and observing the depth of the turbidity in various lights and against various backgrounds. The turbidity is to be exactly imitated by means of the standard solution of carbonate of soda. In order to imitate the turbidity produced by a Winchester quart full of good air only 1 c. c. of this solution of carbonate of soda is required.

If 2 c. c. or more than 2 are required, the air is bad and the ventilation is defective.

In place of the first c. c. of solution of carbonate of soda the carbonic acid naturally present in a Winchester quart of good average air may be used, and a little practice and intelligence will suggest the necessary precautions.

_Estimation of the Oxygen._--To determine this Angus Smith has recourse to the endiometer. Five or six of Bunsen's endiometers were used at once and the mixed gases were exploded by means of a powerful battery and a Ruhumkorff's coil. In his 'Inorganic Chemistry,' Miller thus explains the principle upon which the action of the endiometer is based: "By means of the endiometer various gaseous mixtures may be analysed with great exactness. Many different forms of this instrument are in use. One of the most convenient is Hoffmann's. It consists of a stout syphon tube. (See next figure.) Into the sides of the tube, near the sealed end, two platinum wires (_a_, _b_) are fixed for the purpose of transmitting an electric spark through the cavity of the tube. The sealed limb is accurately graduated to tenths of a c. c. or other suitable divisions. Suppose it be desired to ascertain the proportion of oxygen in atmospheric air. The instrument is first filled with mercury, after which a small quantity of air is introduced; the bulk of the air is accurately measured, taking care that the liquid metal stands at the same level in both tubes, which is easily effected by adding mercury, or by drawing off the mercury if needed, through the caoutchouc tube, which is fixed upon the small inlet tube just above the bend, and which is closed by means of a screw tap (_c_).

A quantity of pure hydrogen, about equal in bulk to the air, is next introduced, and the bulk of the mixture is then accurately measured. The open extremity of the tube is now closed with a cork, below which a column of atmospheric air is safely included. This portion of air acts as a spring, which gradually checks the explosive force, when the combination is effected by passing a spark across the tube by means of the platinum wires. The mixture is then exploded by the electric spark. The remaining gas now occupies a smaller volume, owing to the condensation of the steam which has been formed. Mercury is, therefore, again poured in the open limb until it stands at the same level in both tubes, and the volume of the gas is measured a third time. One third of the reduction of the bulk experienced by the gas will represent the entire volume of oxygen which the mixture contained. Liebig's method is as follows. It is based upon the fact that an alkaline solution of pyrogallic acid absorbs oxygen:

1. A strong measuring tube holding 30 c. c., and divided into one fifth or one tenth c. c., is filled to two thirds with the air intended for analysis. The remaining part of the tube is filled with mercury, and the tube is inverted over that fluid in a tall cylinder widened at the top.

2. The volume of air confined is measured--a quantity of solution of potash of 1·4 sp. grf. (1 part of dry hydrate of potash to 2 parts of water), amounting from 1/40th to 1/50th of the volume of the air, is then introduced into the measuring tube by means of a pipette with the point bent upwards (see _drawing_), and spread over the entire inner surface of the tube by shaking the latter. When no further diminution of volume takes place the decrease is read off. The carbonic acid is thus removed.

3. A solution of pyrogallic acid containing 1 gramme of the acid in 5 or 6 c. c. of water is introduced into the same measuring tube by means of another pipette similar to the above. The mixed fluid (the pyrogallic acid and the solution of potash) is spread over the inner surface of the tube by shaking the latter, and when no further diminution of volume is observed the residuary nitrogen is measured.

4. The solution of pyrogallic acid mixing with the solution of potash of course dilutes it, causing thus an error from the diminution of its tension; but this error is so trifling that it has no appreciable influence upon the results. It may, moreover, be readily corrected by introducing into the tube, after the absorption of the oxygen, a small piece of hydrate of potash, corresponding to the amount of water in the solution of the pyrogallic acid.

There is another slight error on account of a portion of the fluid adhering to the inner surface of the tube, so that the volume of the gas is never read off with absolute accuracy.

In conducting these endiometric experiments the necessary corrections for temperature and barometric pressure must, of course, be made.

_Estimation of the Nitrogen._ The amount of this gas is usually determined by deducting the aqueous vapours, oxygen and carbonic acid, from the volume of air examined.

_Determination of Ammonia and Organic Matter._ These are best determined by drawing a known volume of air through absolutely pure water. To obtain this latter it is best to redistil distilled water, to reject the first portions, then to add an alkaline solution of permanganate of potash, and to discard any portions of the distillate which give the slightest reaction with the Nessler test. The water through which the air is drawn must be kept cool, and afterwards submitted to the proper tests, which will be found under AMMONIA and WATER ANALYSIS. Mr Blyth says, "Solid bodies such as vibrionic germs, dust, fungi, &c., may be obtained by using an aspirator, and drawing the air either through a drop of glycerine or water. Organic matter may also be obtained by suspending glass vessels filled with ice water, over or in the places to be investigated, and submitted to the microscope. High powers, such as immersion lenses, are requisite for the investigation of germs," &c.

Of these germs Dr Angus Smith says:--"They may probably be divided into many kinds--the useful and the deleterious, those which promote health and those which bring disease. The idea of any of them bringing health is not founded on anything positive, but we can scarcely imagine these numberless forms to be all useless. The idea that they bring disease is, I think, one well confirmed." See a paper by the same author "On the Air and Rain of Manchester." 'Memoirs of the Literary and Scientific Society of Manchester,' vol. x. See AIR, VITIATED.

=AIR-GAS.= Air deprived of its carbonic acid and moisture, and then impregnated with the vapours of very volatile fluid hydrocarbons, such as benzine and benzoline, can be used as an illuminating agent. It is requisite, however, to use burners with wide openings, and to apply a low pressure, because if the current be too rapid the flame becomes too much cooled, and is readily extinguished. Apparatus for preparing air-gas have been devised and constructed by Marcus, Mille, Methei, and others.

=AIR-PUMP.= An instrument designed for the removal of air from closed vessels. The simplest form of air-pump is the exhausting syringe, which consists of a cylinder fitted with a stop-cock, and having a valve at the bottom opening inwards. Another valve opening outwards is attached to a piston working inside the cylinder, and by screwing the instrument on to a vessel, and alternately elevating and depressing the piston, all except a very small quantity of residual and comparatively inelastic air is pumped out of the vessel (Figs. _a_ and _b_). The accompanying figures show relative positions of the valve during (_a_) the elevation, and (_b_) the depression of the piston. In the usual and more convenient form of air-pump, a brass tube passes from the bottom of the syringe and terminates in the centre of a disk of brass or glass ground accurately; the vessel from which the air is to be exhausted has its edge very accurately ground, and is mounted upon the plate as shown in the subjoined figure.

=Air-pump, Bunsen's Water.= (See figure on page 53.)

This consists of a wide glass tube, _a_, into which another tube, _b_, _b'_, _b''_, passes air-tight. _c_ is an india-rubber tube connecting a with the water supply, _d_ is a clamp to stop the flow of water through _c_. _e_ is another clamp to regulate the flow, _f_ is a reservoir to prevent any water which may accidentally come over from getting into _j_. _g_ is a plug to let out any water from _f_. _h_ is a screw for connecting a air-tight to a piece of tubing, which should pass 32 feet, if possible, below the level of _a_. _i_ is a piece of strong india-rubber tubing to connect the pump with the vessel to be exhausted. The water rushes in at _c_ and down _h_, carrying bubbles of air with it till the exhaustion is complete. The figure illustrates a common application of this pump to the rapid filtration of liquids which ordinarily pass through paper with difficulty. _a_ is represented as being about half full of water. _k_ is a funnel fixed air-tight in the india-rubber stopper of the bell-jar _j_. _l_ is a small cone of platinum foil to prevent the paper filter which fits into it from being broken. _m_ is a plate of ground glass, _n_ is a beaker to receive the filtrate.

=Air-pump, Sprengel's.= This apparatus depends on the principle of converting the space to be exhausted into a torricellian vacuum.

In the subjoined figure, _c_, _d_ is a glass tube longer than a barometer, open at both ends, and connected by means of india-rubber tubing with a funnel, A, filled with mercury and supported by a stand. Mercury is allowed to fall in this tube at a rate regulated by a clamp at C; the lower end of the tube, _c_, _d_, fits in the flask B, which has a spout at the side a little higher than the lower end of _c_, _d_; the upper part has a branch at _x_ to which a receiver R can be tightly fixed. When the clamp at C is opened, the first portions of mercury which run out close the tube and prevent air from entering below. As the mercury is allowed to run down the exhaustion begins, and the whole length of the tube from _x_ to _d_ is fitted with cylinders of air and mercury, having a downward motion. Air and mercury escape through the spout of the bulb B, which is above the basin H, where the mercury is collected. It is poured back from time to time into the funnel A, to be repassed through the tube until the exhaustion is complete.

=AIRY'S (Dr.) NATURE'S MEDICAL TREATMENT= is the title of a pamphlet which recommends four secret remedies against 166 diseases:

_a._ The Pain Expeller, a mixture of about 35 parts of tincture of capsicum, 20 parts of diluted spirit, and 20 parts of spirit of ammonia.

_b._ Sarsaparillian, a fluid extract of sarsaparilla and China root, containing 1 per cent. of iodide of potassium.

_c._ Pills composed of powdered iron, jalap resin, jalap powder, and marsh mallow powder, made into a mass with some bitter extract. Each pill weighs 0·1 gramme.

_d._ Calming Pastilles are thick, hard tablets, composed of sugar, with oil of anise, and coloured with liquorice juice. (Hager.)

=AKUSTICON= (an ear essence). A proved remedy for every kind of ear disease, by Pserhofer. This may be imitated by dissolving in common glycerine one fifth of its weight of fir tar, filtering, and adding a few drops of cajeput oil dissolved in spirit (Hager.)

=AL-.= [Ar.] An inseparable article equivalent to the English _the_. It is found in many chemical and other words derived from the Arabic; as alchemy, alcohol, alembic, almanac, &c.

=AL'ABASTER.= _Syn._ ALBÂTRE, Fr.; =Alabas'ter=, =Alabastri'tes=, =Alabas'trum=, L. A soft, white species of calcareous and of gypseous stone, used by sculptors. There are several varieties, all of which may be ranged under two heads:--

1. CALCA''REOUS ALABASTER; ORIENT'AL, A.; CALC-SIN'TER. A sub-variety of carbonate of calcium, formed by the deposition of calcareous particles in the caverns of limestone rocks. It has a foliated, fibrous, or granular structure, and a pure, soft, rich, semi-translucent whiteness, generally agreeably variegated with undulating zones or stripes of various shades of yellow, red, or brown. This variety is that most esteemed by sculptors, and for the manufacture of alabaster ornaments. The ancients used it for ointment and perfume boxes. At the baths of San Filippo (Tuscany), the process of its formation may be examined by the observer. The natural spring of boiling water holds carbonate of lime in solution by means of sulphuretted hydrogen, which, escaping into the air, leaves the lime as a precipitate, which is gradually deposited in a concrete form. (M. Alex. Brogniart.)

2. GYP'SEOUS OR COMMON ALABASTER; GYPSUM. A natural hydrated sulphate of calcium, containing a little carbonate of calcium. That from the quarries of the Paris basin contains about 12% of the latter substance. When calcined or roasted, and powdered, it forms the substance known under the name of PLASTER OF PARIS. The more compact, fine-grained specimens of this variety are, like the preceding one, sculptured into almost numberless articles of ornament and utility, such as vases, clock-stands, statuettes, &c. The inferior kinds only are manufactured into the 'plaster of Paris' of the shops. The best specimens are obtained from the lower beds of the gypsum quarries, and are white, and granular, not unlike Carrara marble. It takes a high polish; but from its softness and liability to become discoloured, articles formed of it require more careful treatment than even those of 'calcareous alabaster.'

Alabaster is wrought, turned, and fashioned, in a nearly similar manner to the softer varieties of marble. The tools resemble those employed for the like operations in ivory and brass. Machinery is now often applied to this purpose.

Alabaster is polished, first with pumice-stone, and then with a paste or pap made of whiting, soap, and milk or water; and lastly, with dry flannel. A better method, however, is to rub it first with dried shave-grass (equisetum), and afterwards with finely powdered and sifted slaked lime formed into a paste with water. The surface is then 'finished off' by friction with finely powdered talc or French chalk, until a satiny lustre is produced, or with putty powder, in a similar way to marble.

Alabaster is engraved with tools resembling those employed for other soft minerals. It is etched by covering every part of the surface, except that to be acted on, with a solution of white wax in oil of turpentine (1 to 4), thickened with a little finely powdered white lead, and subsequent immersion in water acidulated with acetic acid or hydrochloric acid, for the calcareous variety; and in spring water, for 20 to 50 hours (according to the effect desired), for the gypseous variety. The varnish is washed off with oil of turpentine, and the etched parts carefully brushed over with finely powdered gypsum.

Alabaster is joined and repaired by means of white of egg, or rice glue, thickened with finely powdered quicklime; or by a paste of newly baked and finely powdered gypsum, mixed up with the least possible quantity of water.

Calcareous alabaster is usually cleaned with a brush and warm soap-and-water, or with tepid water to which a few grains of carbonate of soda or of ammonia have been added; followed in either case by rinsing in clean water. If much discoloured, thoroughly cover the article with a paste of freshly slaked lime and water, and let it remain twenty-four hours; then wash off the paste with soap and water, rubbing hard the stains.

Delicate objects in gypseous alabaster can only be safely cleaned with benzol, or with pure oil of turpentine. If necessary, the surface must be repolished. Grease spots may be removed from either variety with a little benzol or oil of turpentine.

Alabaster is occasionally stained or coloured, and, for the calcareous variety, in a similar way to marble, except that heat is not employed; and for the gypseous variety, in the manner noticed under PLASTER OF PARIS. The gypseous variety is also bronzed and hardened in a similar way to that adopted for casts in the latter substance.

_Obs._ Gypseous alabaster is dissolved by water; and the beauty of both varieties is almost irrecoverably destroyed by grease, coloured oils, varnishes, smoke, &c. It is, therefore, unfitted for garden ornaments, or other objects exposed to the rain or weather, unless it be painted or bronzed; and is even then very perishable. Contact with acids, alkalies, and ammoniacal and sulphurous fumes, also injure, and, if prolonged, destroy it. Even an uncorked phial of smelling-salts placed on a mantel-piece beside an alabaster vase will soon destroy its beauty. Thus, all delicate objects in alabaster should be protected by a glass shade.

=Alabaster, Orient'al= (Factitious). Figures, basso relievos, &c., of considerable hardness and beauty, may be formed by imitating the process adopted at the baths of San Filippo, before referred to.

_Proc., &c._ Moulds of sulphur are placed either vertically or obliquely in an open tub or cistern, having a freely perforated bottom. Surmounting the whole are two or more pieces of wood in the form of a cross or star. The sulphurous calcareous water, falling on this cross, is scattered into spray or streamlets, and losing the gaseous portion which holds the lime in solution, deposits it in the form of oriental alabaster on the surface of the moulds. In from 1 to 4 months, according to the nature of the article, a sufficiently thick deposit is obtained. The object is then removed from the mould, and trimmed and polished. It is found that the more vertical the position of the mould, the finer is the grain of the resulting deposit. The water of the Spring of San Filippo may be exactly and easily imitated by the chemist; and the whole process offers a new and valuable ornamental art for the amusement and profit of the ingenious and enterprising.

=Alabaster, Shand's Chinese.= Carbonate of lime. (Chandler.)

=Alabaster Tablets, John Swine's Chinese.= Carbonate of lime. (Chandler.)

=ALAMODE'= ([)a]l-[)a]h-m[=o]dé). [Fr., _à la mode_.] According to the prevailing mode or fashion. In _cookery_, applied to several dishes, but more particularly to one of beef (alamode beef), commonly shortened by the lower class of Londoners into "alamode." See BEEF, STEWING, &c.

=ALAN'TINE.= [Eng., Fr., Ger.] _Syn._ ALANTI'NA, L. A substance identical with inulin, found in the roots of garden angelica ('angelica archangelica,' Linn.).

=ALBA'TA.= [L., Eng.] A name given to several alloys resembling silver. See ALLOYS, GERMAN SILVER, &c.

=ALBION= (Parisian). "Will preserve the skin white and free from wrinkles." An aromatic water with chloride of lead and calomel suspended in it. (Landerer.)

=ALBOLITH.= A cement powder prepared by W. Riemann, Breslau. Made with calcined magnesia (obtained from magnesite) and chloride of magnesium. It is recommended for painting walls, stairs, and wooden articles. (Hager.)

=ALBU'MEN.= [Eng., L.] _Syn._ ALBUMIN; ALBUMINE, Fr.; EIWEISS, EIWEISTOFF, Ger. Literally, the white of egg; a peculiar nitrogenous substance which enters largely into the composition of animal bodies. It abounds in the blood, muscles, bones, coagulable lymph, vitreous and crystalline humour of the eye, fluid of dropsy, &c. The white of egg consists of nearly pure albumen dissolved in water.

A substance identical with albumen is found in many vegetables. It enters largely into the composition of all the emulsive seeds. According to Seguin, it exists in considerable quantity in all those vegetables and fruits that afford a vinous liquor without the addition of yeast.

_Prep._ The white of egg and the serum of blood, when strained through muslin, furnish albumen, in solution, in a sufficiently pure state for all the ordinary purposes of the arts. Pure solid albumen may be prepared as follows:--

1. Agitate strained white of egg with 10 or 12 times its bulk of alcohol, collect the precipitated flocculi on a muslin filter, and suffer it to dry at a temperature not exceeding 120° Fahr.

2. Add a little water to white of egg, mix, filter, exactly neutralise with acetic acid, and then largely dilute with pure cold water; the precipitate which falls may be collected on a filter and washed. Strained serum of blood may be used instead of white of egg, in both the above forms.

_Comp._, _&c._ The following is the composition of albumen according to Lieberkühn:--

Carbon 53·3
Hydrogen 7·1
Nitrogen 15·7
Oxygen 22·1
Sulphur 1·8
----
100·0

Chatin found iodine in the white of egg; it also contains chloride, sulphate, phosphate, and carbonate of sodium, phosphate of calcium, and traces of potassium in it; but, unlike the sulphur, none of these substances form a constituent part of pure albumen, though probably always present in white of egg.

_Prop._ Pure solid albumen (unaltered by heat) is nearly colourless, inodorous, and tasteless; scarcely soluble in water, but readily so in water, containing an exceedingly small quantity of caustic soda or potash, and in a strong solution of nitrate of potassium. When dried by a gentle heat it shrinks into a translucent horny mass; and when exposed to a sufficient temperature, yields the usual ammoniacal odour and products of animal matter. Its solution (as white of egg) is solidified or coagulated by a heat of from 145° to 165° Fahr., forming a white, opaque mass; when very dilute, on boiling (only) it separates in fine light flocks. When thus coagulated, it is insoluble in water at a less temperature than 302° Fahr. (Wöhler and Vögel), unless alkalised. Ordinary solutions of albumen give precipitates with sulphuric, hydrochloric, nitric, and metaphosphoric acids, with tannin and astringent solutions, and with most of the metallic salts; but are not affected by either acetic acid or tribasic (common) phosphoric acid. Alcohol, in quantity, also precipitates albumen. Strong oil of vitriol turns it black in the cold, but on applying a gentle heat, a gorgeous, red-coloured liquid is produced. Strong hydrochloric acid gives a deep violet-blue solution. White of egg or serum exposed in a thin stratum to the air, dries up into a pale, yellow, gum-like substance, and in this state may be kept for any length of time, retaining its property of redissolving when immersed in slightly warm water.

_Tests._--1. Both heat and alcohol (or strong spirit) coagulate it:--2. A solution of perchloride of mercury dropped into a fluid containing albumen occasions a white precipitate:--3. Subacetate of lead acts in the same way. Either of the last two will render turbid a solution containing only the 1-2000th part of fresh white of egg, or the 1-10,000th part of dry albumen:--4. Tannin and tincture of galls give yellow, pitchy precipitates:--5. If dry caustic potash or soda be triturated with either liquid or solid albumen, ammoniacal fumes are evolved, and the mixture on calcination yields ferrocyanide of potassium:--6. Its coagulability by heat, and its incoagulability by acetic acid, distinguish it from casein.

_Uses, &c._, Independently of its value as an alimentary substance, albumen is largely employed in photography as a glaze or varnish, for fixing colours in calico printing, as a cement, &c., and more particularly as a clarifier for wines, syrups, vegetable solutions, and other liquids. Its efficacy for the last purpose depends on its entangling the impurities in its meshes during coagulation, and either rising to the surface with them as a 'scum,' or sinking with them as a precipitate. In France it is prepared on an extensive scale, at the abattoirs, by being spread in thin layers to dry; the source of supply being of course the stream of the blood of the slaughtered animals. When the liquid operated on does not spontaneously coagulate albumen, it is necessary to apply heat to it. In cases of poisoning by the mineral acids, corrosive sublimate, nitrate of silver, sulphate of copper, bichloride of tin, or sugar of lead, the white of egg (or indeed the yolk as well) is one of the best antidotes that can be administered.

=Albumen, Flake.= _Syn._ ALBUMEN IN POWDER, SOLID A., SOLUBLE A., PLANTER'S A. _Prep._ Expose strained white of egg or serum of bullock's blood, in a thin stratum, to a current of dry air, until it concretes into a solid transparent substance, resembling horn. In this state it may be kept any length of time, or it may be further dried until brittle, and then reduced to coarse powder.

_Use._ It is extensively employed as a 'clarifier' in the sugar plantations of the West Indies, and elsewhere. It is prepared for use by soaking and stirring it with cold water until it is dissolved, when it is whisked to a froth in the usual way, and agitated with the liquid to be clarified.

=Albumen, Iodised.= 1. To the white of every egg employed add 7-1/2 grains of iodide of potassium dissolved in an equal weight of distilled water. Beat the mixture to a froth, let it stand until insoluble matters have settled, pour the clear portion into a wide-mouthed bottle, and keep in a cool place. 2. Dissolve 50 grains of iodide of potassium and 10 grains of bromide of ammonium in 2-1/2 oz. of distilled water, and add 120 minims of strong liquor ammoniæ. Add this solution to 10 oz. of albumen, let the mixture stand to settle, and filter. This preparation is said to keep good for a long time.

=Albumen, Solution of (B. P.).= Take of white of one egg; distilled water, four fluid ounces. Mix by trituration in a mortar, and filter through clean tow, first moistened with distilled water. This solution must be recently prepared.

=Albumen, Vegetable.= This substance, long considered to be a distinct proximate principle peculiar to the vegetable kingdom, has been shown, by recent researches, to be identical with animal albumen. It is particularly abundant in carrots, turnips, cabbages, green stems of peas, and oleaginous seeds.

=ALBU'MEN.= In _botany_, the solid, fleshy, or horny substance found in many seeds, between the integuments and the embryo. It is the part that furnishes the flour of the 'cereals,' the flesh of the 'cocoa-nut,' and the great mass of the seeds of coffee and other vegetables. However poisonous the plants which produce it may be, this substance is never deleterious.

=ALBUMENISED PAPER.= A French paper highly glazed, having a fine surface, and made by Rive; a German paper having a more uniform texture, and made by Saxe; also a paper by Towgood, are recommended for the preparation of albumenised paper. Positive paper may be albumenised as follows:--Add 15 grains of finely pulverised common salt to the white of every egg used, and whisk until the mixture is entirely converted into a white froth. Allow this froth to stand in a glazed earthenware pan which must be rather larger than the sheets of paper to be albumenised, for about twelve hours. At the end of this pour the clear portion of the liquid into a flat porcelain tray. Mark the inferior side of the paper, slightly damp it, lift it by its ends, and float it carefully on the prepared albumen, keeping its inferior and dry side uppermost. Then raise the paper at each end, and if any air bubbles are seen remove them with a card or brush and replace the paper in the bath. Remove the paper from the bath and suspend it at the corners by clips. Albumenised paper should be kept dry by enclosing it in tin or zinc cases.

=ALBUMENOIDS.= A term applied to albumen, fibrin, casein, and similar bodies.

=ALBU'MENOUS.= _Syn._ ALBUMINO'SUS, L.; ALBUMINÉ, ABUMINEUX, Fr.; EIWEISSTOFFHALTIG, Ger. Formed of, containing, or having the properties of albumen.

=Albuminous Plants=. In _botany_, all plants whose seeds contain albumen in a separate state; as in the cereals, palms, &c.

=Albuminous Principles _or_ Substances.= Albumen, casein, fibrin, gluten, &c.

=ALBURN'UM.= [L.] _Syn._ ALBURN*; SAPWOOD. In _botany_, the white and softer parts of the wood of exogenous plants, lying between the inner bark and the heartwood. It consists of empty or nearly empty tubes or cells, which gradually acquire solidity by the deposition of resins, tannin, and other products of vegetation, and in time becomes wood. It is through the alburnum that the ascending sap chiefly flows.

=ALCARAZ'ZA.= [Sp.] A species of porous earthenware, or a vessel formed of it, made in Spain from a light, sandy marl, and but slightly fired. Their value as 'coolers' arises from the copious evaporation of the water, which gradually transudes. A similar ware and articles are made in France, under the name of HYGROCERA'MEN; and in England, under the names of POROUS WARE, WATER COOLERS, WINE COOLERS, BUTTER COOLERS, &c. The following are forms said to be used in our potteries:--

_Prep._ 1. Take of sandy marl, 2 parts; brine, q. s.; make a dough, and then knead in of common salt, in fine powder, 1 part. Bake the pieces slowly, and lightly.

2. Good clay, 2 parts; fine siliceous sand, 3 parts; brine, q. s.; common salt, 1 to 2 parts; as before.

3. Powdered clay, 2 parts; powdered charcoal, 3 parts (by weight); water q. s. to form a stiff dough. The kilning must be so arranged that the heat is applied gradually, and the vessels exposed to a current of hot air; and it must be continued until all the charcoal is burnt out, carefully avoiding over-firing.

=AL'CHEMY= (-k[)i]m-). _Syn._ AL'CHYMY (-k[)i]m-); HERMETIC ART*; ALCHEM'IA, ALCHYM'IA, L.; ALCHIMIE, Fr.; ALCHEMIE, Ger.; ALCHIMIA, It. The romantic forerunner of the modern science of chemistry. An imaginative art or science, having for its objects the discovery of a substance (PHILOSOPHER'S STONE) capable of transmuting the baser metals into gold--a panacea, or universal remedy (ELIXER VITÆ), by which disease and death were to be avoided by its possessor--an alkahest, or universal solvent--a universal ferment; and other like absurdities. A mixed metal formerly used for utensils was also called by this name.

=AL'COHOL.= C_{2}H_{6}O. [Eng., L.; B. P.] _Syn._ AL'KOHOL, Eng., L.; ALCOÖL, ALCOHOL, Fr.; ALKOHOL, HÖCHST RECTIFIEIRTER WEIN-GEIST., Ger.; ALCOÖLE, It. A term commonly applied to one kind of spirit--that obtained by the distillation of any fermented saccharine liquid, and forming the characteristic principle of wines, beers, spirits, and other intoxicating liquors.

_Etym._ Kohol, a Hebrew-Syriac word, is the name given to a preparation of powdered antimony used by Oriental ladies to paint their eyebrows. In course of time this term was applied to other fine powders, and ultimately to highly rectified spirits.