Chapter XXIV: Letter XIX: gives a definition of the ellipsis, which would be a (18)

A few drops of bromine were then added to the water, which soon acquired a yellow colour, by dissolving a small portion of the substance; being now included in the voltaic circuit, the galvanometer needle was deviated 70°, and an abundant disengagement of gas took place from the platina wires. These were oxygen and hydrogen, in the usual proportion, proving that the water only had been decomposed.

From these experiments it results, that a body which does not at all conduct voltaic electricity, or at least but very badly, namely, _pure water_, may be rendered a very good conductor, by its mixture with a few drops of perfectly _non-conducting_ substance, namely, _bromine_. M. de la Rive has found the same fact to occur with iodine, and iodine and water; and his father had observed, in a course of experiments made a long time ago on the conducting power of fluids, that diluted sulphuric acid is a better conductor than very much concentrated acid: may not anhydrous sulphuric acid then be a non-conductor like bromine, &c.?—_Annales de Chimie_, xxxv. 161.

FOOTNOTE:

[129] See, on this point, the statement by M. Becquerel, p. 462, relative to the use of platina wires, when forming a communicating medium with fluids.

5. _Elementary Nature of Bromine_.—Iodine colours a solution of starch blue, bromine renders a similar solution orange colour. M. A. de la Rive added a few drops of bromine to a solution of starch [p466] coloured blue by iodine, and obtained a compound which gave two distinct colours with starch, one brown, the other yellow; the difference of colour corresponding with the two bromides of iodine described by M. Balard. These compounds of iodine and bromine, dissolved in a solution of starch, were subjected to the voltaic pile: immediately the yellow solution became blue about the negative pile, and orange about the positive pile, indicating the separation and places of the iodine and bromine. Thus the smallest quantity of iodine may be discovered in bromine; but when the experiment was resorted to, to prove whether the idea thrown out, that bromine was a compound of chlorine and iodine, was founded in fact or not, it gave no such indication, and a solution of bromine in starch electrified for a long time together, gave no appearance of iodine. Hence M. de la Rive concludes, that bromine contains no iodine, but is an element analogous to iodine and chlorine.

When bromine and iodine are combined, the former passes to the positive pole, and is consequently more negative than the latter; which accords with the observation of M. Balard, that it should occupy a place between chlorine and iodine.

According to the _Bulletin Universelle_, when the letter to M. Arago, containing an account of the facts above referred to, was read to the Academy of Sciences, that body decided that the assertion of M. Dumas that bromine was a compound of chlorine and iodine should be considered as retracted, and that it should be so entered, upon the procès-verbal of the sitting.—A. viii. 209.

6. _Quantity of Bromine in Sea-Water_.—One hundred pounds of sea-water, taken up at Trieste, treated by chlorine, ether, &c., according to M. Balard’s process, produced five grains of bromide of sodium, or 3.278 grains of bromine. It would appear that, in the sea-water of Trieste, the bromine is unaccompanied by any iodine, and the same is the case, according to M. Hermbstadt, with the waters of the Dead Sea. In the water of the Mediterranean, on the contrary, iodine always appears with the bromine.

7. _Sale of Bromine_.—The discoverer of bromine, M. Balard, has been enabled, by his improvements, to prepare that peculiar body in quantities sufficient to permit its sale. It may be obtained at his shop, Rue Argenterie à Montpellier, or at M. Quesneville’s manufactory of chemical substances at Paris. The price is four francs the gros (about 60 grains), fourteen francs the half ounce, and twenty-three francs the ounce.

8. _Preparation of Iodous Acid_.—M. Pleischl says that, in preparing this acid, three parts of chlorate of potash with one of iodine are to be used, and not equal parts according to M. Sementini; and also that it is indispensable to cool the receiver considerably during the whole operation. [p467]

9. _On a peculiar Nitric Acid, and Sulphate of Potash, by_ Mr. Phillips.—For the purpose of preparing nitric acid of the greatest strength, Mr. Phillips mixed 70 parts of nitre with 70 parts of oil of vitriol, S. G. 1.8442 at 60°, and distilled for eight hours. The nitric acid obtained was reddish yellow, weighed 46.13 parts, was of S. G. 1.5033, and by an experiment on carbonate of lime, was found equivalent to 34.24 of that substance; the latter fact indicates that 36.98 of real acid was present, and the liquid acid therefore consisted of

Real nitric acid 36.98 or 80.16
Water 9.15 19.84
----- ------
46.13 100.00

Supposing this acid to be a definite compound of two atoms of acid, 108, and three of water 27, it would consist of

Real acid 36.90 or 80
Water 9.23 20
----- ---
46.13 100

The salt remaining in the retort weighed 92.87 parts; nearly this weight of water being added and heated, the whole was dissolved, and on cooling, a salt, consisting of extremely minute filaments resembling asbestos, was obtained, which, by capillary attraction, retained a part of the residual solution so powerfully, that it was necessary to absorb it by filtering paper.

Although it appeared improbable that the crystals could be a variety of the known form of bisulphate of potash, yet supposing it might be that salt with either less, or more than two atoms of water, Mr. Phillips proceeded to its analysis. Some of the salt was readily dried by exposure to the air of a warm room: 100 grains, by muriate of baryta gave 154.75 grains of sulphate of baryta, equivalent to 52.45 sulphuric acid: 109 grains heated to redness, lost 21.6 sulphuric acid and water, and left 78.4 grains of neutral sulphate of potash. The latter contain 35.6 grains of sulphuric acid, which, subtracted from the whole quantity of 52.45, indicates 16.85 as the quantity dissipated by heat; and this again, subtracted from the 21.6, indicates 4.75 water in the crystals. The quantity of acid separated by heat is, therefore, very nearly half that remaining in the neutral sulphate, and the salt in question appears to be a sesquisulphate of potash, consisting of

theory. experiment.
3 atoms sulphuric acid 120 55.33 52.45
2 " potash 96 42.66 42.80
1 atom water 9 4.00 4.75
--- ----- ------
225 99.99 100.00

Mr. Phillips found it difficult to prepare the sesquisulphate free [p468] from bisulphate; and on repeating the attempt to procure it exactly as before, obtained a large quantity of bisulphate, and a small quantity of the peculiar salt; although the quantity of water present is known to have an important influence on the nature of the sulphates produced, yet the precise circumstances on which the formation of sesquisulphate depends, are at present unknown.—_Phil. Mag. N. S._, ii. 429.

10. _On certain Properties of Sulphur_.—The effect of heat upon sulphur in first fusing it, but afterwards causing diminution of fluidity in a certain degree proportionate to the temperature, has been long and generally known, as well also as the peculiar soft state into which the sulphur may be brought, by pouring it, when hot and thickened, into cold water. M. Dumas has been led to examine these phenomena for the purpose of acquiring a precise and particular knowledge of the effects and changes.

Fused sulphur began to crystallize between 226° and 228°. Its fusing point may be considered as 226°.4. Between 230° and 284° it is as liquid as a clear varnish, and of the colour of amber; at about 320° it begins to thicken, and acquire a red colour; on increasing the heat, it becomes so thick, that it will not pour. This effect is most marked between 428° and 572°; the colour being then a red-brown. From 572° to the boiling point it becomes thinner, but never so fluid as at 248°. The deep red-brown colour continues until it boils.

When the most fluid sulphur is suddenly cooled, it becomes brittle, but the thickened sulphur, similarly treated, remains soft, and more soft as the temperature has been higher. Thus, at 230°, the sulphur was very liquid, and yellow; and cooled suddenly by immersion in water, it became yellow and very friable; at 374° it was thick, and of an orange colour, but by cooling, became at first soft and transparent, but soon friable, and of the ordinary appearance; at 428°, it was red and viscid, and when cooled, soft, transparent, and of an amber colour; at the boiling point it was deep brown red colour, and when cooled very soft, transparent, and of a red-brown colour.

It is not necessary, as is sometimes stated, to heat the sulphur a long time to produce this effect; all depends upon temperature. The only precaution necessary is, to have abundance of water, and to divide the sulphur into small drops or portions, that the cooling may be rapid. If it be poured in a mass, the interior cools slowly, and acquires the ordinary hard state. When the experiment is well made at 446°, the sulphur may be drawn into threads as fine as a hair, and many feet in length.

M. Dumas, in remarking upon this curious effect of sudden cooling, classes it with the similar effect which occurs with bronze. Although difficult to assign the exact cause, yet he notices that the tendency to crystallize can evidently be traced as influential over some of the appearances, the hardness and opacity, for instance, [p469] which always occur together when the crystalline state is assumed; whereas, when rapid cooling has hindered crystallization, the mass remains soft and transparent, until it crystallizes, which usually happens in twenty or thirty hours.—_Ann. de Chimie_, xxxvi. 83.

11. _On the Fluidity of Sulphur and Phosphorus at common temperatures_, by Mr. Faraday.—I published some time ago a short account of an instance of the existence of fluid sulphur at common temperatures[130]; and though I thought the fact curious, I did not esteem it of such importance as to put more than my initials to the account. I have just learned, through the _Bulletin Universel_ for September, p. 178[131], that Signor Bellani had observed the same fact in 1813, and published it in the _Giornale di Fisica_, vol. vi. (old series). I also learn, by the same means, that M. Bellani complains of the manner in which facts and theories, which have been published by him, are afterwards given by others as new discoveries; and though I find myself classed with Gay-Lussac, Sir H. Davy, Daniell, Bostock, &c., in having thus erred, I shall not rest satisfied, without making restitution, for M. Bellani, in this instance, certainly deserves it at my hand.

Not being able to obtain access to the original journal, I shall quote M. Bellani’s very curious experiments from the Bulletin, in which they appear to be fully described. “The property which water possesses, of retaining its fluid states, when in tranquillity, at temperatures 10° or 15° below its freezing point, is well known; phosphorus behaves in the same manner; sometimes its fluidity may be retained at 13° (centigrade?) for a minute, an hour, or even many days. What is singular is, that, though water cooled below its freezing point, congeals easily upon slight internal movement, however communicated, phosphorus, on the contrary, sometimes retains its liquid state even at 3°, even though it be shaken in a tube or poured upon cold water. But, as soon as it has acquired the lowest temperature which it can bear without solidifying, the moment it is touched with a body at the same temperature, it solidifies so quickly, that the touching body cannot penetrate its mass. If the smallest morsel of phosphorus is put into contact with a liquified portion, the latter infallibly solidifies, though it be only a single degree below the limit of temperature necessary; this does not always happen when the body touching it is heterogeneous.

“Sulphur presented the same phenomena as phosphorus; fragments of sulphur always produced the crystallization of cold fluid portions. Having withdrawn the bulb of a thermometer which had been plunged into sulphur at 120°, it came out covered with small globules of sulphur, which remained fluid at 60°; and having touched these one after another with a thread of glass, they became solid: although several seemed in contact, yet it required that each [p470] should be touched separately. A drop of sulphur, which was made to move on the bulb of the thermometer, by turning the instrument in a horizontal position, did not congeal until nearly at 30°; and some drops were retained fluid at 15°, _i. e._ 75° of Reaumur below the ordinary point of liquefaction.”

The _Bulletin Universel_ then proceeds to describe some late and new experiments of M. Bellani, on the expansion in volume of a cold dense solution of sulphate of soda during the solidification of part of the salt in it. The general fact has, however, been long and well known in this country and in France; and the particular form of experiment described is with us a common lecture illustration. The expansion, as ascertained by M. Bellani, is 2/87 of the original volume of fluid.

According to the Bulletin, M. Bellani also claims, though certainly in a much less decided manner than the above, the principal ideas in a paper which I have published on the existence of a limit to vaporization, and I referred back to the _Giornale di Fisica_ for 1822, (published prior to my paper,) for the purpose of rendering justice in this case also. Here, however, the contact of our ideas is so slight, and for so brief a time, that I shall leave the papers in the hands of the public without further remarks. It is rather curious to observe how our thoughts had been at the same time upon the same subject. Being charged in the Bulletin with quoting an experiment from a particular page in M. Bellani’s memoir, (which I did from another journal, in which the experiment only was described,) I turned to the original place, and there, though I found the experiment I had transferred, I also found another which I had previously made on the same subject, and which M. Bellani had quoted.

I very fully join in the regret which the _Bulletin Universel_ expresses, that scientific men do not know more perfectly what has been done, or what their companions are doing; but I am afraid the misfortune is inevitable. It is certainly impossible for any person who wishes to devote a portion of his time to chemical experiment, to read all the books and papers that are published in connexion with his pursuit; their number is immense, and the labour of winnowing out the few experimental and theoretical truths which in many of them are embarrassed by a very large proportion of uninteresting matter, of imagination, and of error, is such, that most persons who try the experiment are quickly induced to make a selection in their reading, and thus inadvertently, at times, pass by what is really good.

FOOTNOTES:

[130] Quarterly Journal of Science, xxi. 392.

[131] The Italian Journal has not yet arrived in this country.

12. _Separation of Selenium from Sulphur_.—Berzelius says, that these substances, so much resembling each other in their general properties, may be easily separated by the following process. When sulphuret of selenium is fused with carbonate of potash, the alkali not being excess, the fused mass, dissolved in water, leaves selenium undissolved and free from sulphur. [p471]

Some of the sulphuret of selenium from Lukawitz, in Bohemia, was dissolved in potash, and the solution converted into hyposulphite by exposure to the air at the temperature of 65° F.; 0.1125 of the sulphuret experimented with were precipitated, and found to be _pure selenium_. The solution being of a deeper red colour than that of the common sulphuret, a piece of sulphur was put into it, and the whole boiled for a moment; a quarter of a grain of selenium, perfectly free from sulphur, was precipitated.

A solution of a neutral seleniate, or of one with excess of base, is soon rendered turbid by having sulphuretted hydrogen passed through it. At first pure selenium separates; afterwards sulphuret of selenium; and, lastly, mere sulphur. The solution should be considerably diluted; when concentrated, the precipitate formed is of a flame yellow colour, but soon becomes brownish-black, and sulphur is deposited, sometimes crystallizing at the surface of the deposite.—_Phil. Mag., N. S._, ii. 390.

13. _On a new Compound of Selenium and Oxygen—Selenic Acid, by_ MM. Mitscherlich and Nitzsch.—This acid contains half as much more oxygen as that discovered by M. Berzelius, and with potash forms a neutral salt, having the same form and optical properties as sulphate of potash, containing no water when crystallized, and producing insoluble precipitates with barytic salts. The acid is isomorphous with the sulphuric, and may with propriety be called _selenic acid_, that described by M. Berzelius being considered as the _selenious acid_.

The new acid is easily prepared: for this purpose selenium, selenious acid, a selenite or a metallic selenuret is to be fused with nitre. Selenuret of lead, being the most abundant source, has been used for this purpose, but being accompanied by sulphuret, the selenic acid is usually contaminated by sulphuric acid. The selenuret of lead is to be freed from carbonates by muriatic acid, and the residue mixed with its weight of nitrate of soda, and thrown gradually into a red-hot crucible. Water then dissolves out seleniate nitrate and nitrite of soda, no selenium remaining in the residue. The solution quickly boiled, deposits anhydrous seleniate of soda, and this being separated, by cooling crystals of nitrate of soda are formed; these being removed, ebullition again causes more seleniate to fall down, and proceeding in this way an imperfect separation is effected. The seleniate, like the sulphate of soda, is most soluble in water at 181°. To purify the salt completely, the nitrite should be changed into nitrate by nitric acid; but then sulphate of soda would remain as an impurity formed from sulphuret in the ore, and no attempt to separate this has as yet succeeded.

But if the seleniate of soda be mixed with muriate of ammonia and heated, selenium, nitrogen and water come over, no trace of sulphur appearing. The selenium may, however, be dissolved in excess of nitric acid, and the selenious acid produced tested by [p472] muriate of baryta, which would then separate sulphuric acid if present; the clear solution is to be saturated with carbonate of soda, evaporated to dryness, and the mixture of selenite and nitrate of soda obtained, fuzed in a porcelain crucible over a spirit-lamp. Then proceed by crystallization as before, and a pure seleniate of soda will be produced.

To separate the selenic acid, the solution is to be decomposed by nitrate of lead; the seleniate of lead is as insoluble as the sulphate, and being well washed, is to be decomposed by a current of sulphuretted hydrogen, which has no action on the selenic acid; the solution being filtered, is to be boiled, and is then diluted selenic acid. Its purity, as respects fixed bodies, is ascertained by its entire volatility; if sulphuric acid be present, it may be ascertained by boiling a portion with muriatic acid, which produces selenious acid, and then testing by muriate of baryta, a precipitate indicates sulphuric acid.

From the isomorphism of selenic acid and its salts with sulphuric acid and its salts, M. Mitscherlich concluded, that the oxygen in the acid should be to that in selenious acid as 3 to 2; and to that in bases when it forms salt, as 3 to 1. These views were confirmed by experiments. From the decomposition of seleniate of potash by muriate of baryta, it appeared that the seleniate was composed of

Potash 42.16 oxygen 7.15
Selenic acid 57.84 ---- 21.79
------
100.00

The composition of the acid was determined by boiling a certain weight of the seleniate of soda with muriatic acid in excess, and decomposing the selenious acid formed by sulphite of soda; 4.88 of the salt gave 2.02 of selenium, from which, and the above result, it would appear that the acid is formed of

Selenium 61.4
Oxygen 38.6
-----
100.0

According to Berzelius, selenious acid consists of 100 selenium, and 40.33 oxygen; and supposing this contains two-thirds the oxygen in selenic acid, the latter should consist of 62.32 and 37.68. From the analysis above given of the seleniate of potash, it is evident that 100 of selenic acid saturates a quantity of base captaining 12.56 of oxygen, which would agree with the latter estimate of selenic acid.

_Selenic acid_ is a colourless liquid, which may be heated to 536°, without sensible decomposition; above that it changes, and is, rapidly resolved into oxygen and selenious acid at 554°. Heated to 329°, its specific gravity is 2.524; at 512°.6 it is 2.6; at 509° it is 2.625; but by that time selenious acid has been formed in it. A portion of concentrated acid, from which the selenious acid had [p473] been removed, consisted of 84.21 selenic acid, and 15.75 water; but it is certain that the selenic acid begins to decompose before it has resigned the last portions of water.

Selenic acid has a powerful attraction for water, and evolves much heat when mixed with it. It is not decomposed by sulphuretted hydrogen; so that the latter body may be used to decompose the seleniates of lead and copper. When boiled with muriatic acid it produces selenious acid and chlorine, and the mixture, like aqua regia, will dissolve gold or platina. Selenic acid dissolves zinc and iron, evolving hydrogen; it dissolves copper, evolving selenious acid; and it dissolves gold, but not platina. Sulphurous acid has no action on selenic acid, but instantly decomposes the selenious acid. A solution containing selenic acid is easily decomposed, by first boiling it with muriatic acid, and then adding sulphurous acid.

Selenic acid is but little inferior to sulphuric acid in its affinity for bases; seleniate of baryta is not completely decomposed by sulphuric acid. Its combinations being isomorphous with those of sulphuric acid, and possessing the same crystalline forms, and the same general chemical properties, present but very slight, though very interesting differences from the sulphates. These will be resumed by M. Mitscherlich in a future memoir, with the express object of illustrating the theory of Isomorphism.—_Ann. de Chimie_, xxxvi. 100.

14. _Preparation of Hyposulphuric Acid_.—According to M. Heeren, to obtain the greatest quantity of this acid in the process of passing sulphurous acid over black oxide of manganese, the temperature should be low, and the oxide finely divided. The largest portion of hyposulphuric acid is formed at the commencement of the operation.

15. _Singular Habitude of Phosphoric Acid with Albumen_.—MM. Berzelius and Englehart differed in their results respecting the effect of phosphoric acid on albumen; the latter found the acid caused precipitation of the substance, the former the reverse. Fortunately coming into company, they made some experiments, and discovered a very singular property of the acid. The acid in Berzelius’s laboratory not precipitating albumen, Dr. Englehart prepared a fresh portion from phosphorus and nitric acid, evaporating the solution in a platina vessel, and heating it to redness. This acid, dissolved in water, precipitated both animal and vegetable albumen abundantly. Another portion of acid, prepared by burning phosphorus in air, also precipitated albumen. After many experiments to discover the cause of difference in the acids, Dr. Englehart remarked, that the two acids he had prepared, gradually lost their power of precipitating albumen, and in some days were like the acid of Berzelius. This change took place both in open and closed vessels, and was not at all hastened by ebullition. [p474] Upon evaporating the acid, and heating it to redness, it recovered its precipitating power, but gradually lost it again by a day’s repose. The cause of this difference escaped detection; it evidently does not depend upon a difference of oxidation. “May it not be supposed,” says Berzelius, “that there exists a chemical combination of phosphoric acid with water, which is not formed until some time after solution, and which is incapable of precipitating albumen?”—_Annales de Chimie_, xxxvi. 110.

16. _Economical Preparation of Deutoxide of Barium_.—This process is due to M. Quesneville. Nitrate of baryta is to be put into a luted earthenware retort, to which a tube is to be attached for the purpose of conveying the liberated gases to a water-trough. The retort is to be gradually heated to redness, and retained at that temperature as long as nitrous acid and azotic gas pass over; the evolution of these substances indicates that nitrate of baryta still remains to be decomposed, but the instant that pure oxygen gas passes off, the fire is to be removed and the retort cooled. The product of this decomposition is a peroxide of barium; it falls to pieces in water, without producing heat, disengages oxygen when boiled with water, and is reduced to a protoxide by a strong heat. When acted upon by sulphuric acid, no nitric acid was evolved; and when subjected to nitric acid, no nitric oxide was produced. The production of this peroxide is easily understood, for the protoxide formed by the decomposition of the nitrate being in contact, at a red heat, with a large quantity of oxygen in a nascent state, combines with it, and is retained, unless the heat be so high as to decompose it.—_Annales de Chimie_, xxxvi. 108.

The decomposition and effect are precisely the same as those lately pointed out by Mr. Phillips as occurring with potassium when the nitrate of potash is decomposed by heat.—See p. 483 of the last volume of this Journal.

17. _Preparation of Aluminum—Chloride of Aluminum_.—According to the accounts published, the following process has succeeded in the hands of M. Oersted, in decomposing alumina and evolving the base _aluminum_. Pure alumina is to be heated to redness, and then well mixed with pulverized charcoal; the mixture is to be placed in a porcelain tube, and being heated to redness, is to have dry chlorine gas passed over it; the charcoal reduces the alumina, the base combines with the chlorine, and oxide of carbon is formed. The chloride of aluminum is soft, crystalline, and evaporates at a temperature a little above 212° Fahrenheit: it readily attracts moisture from the atmosphere, and becomes hot when water is added to it. Being mixed with an amalgam of potassium, containing much of the latter metal, and immediately heated, chloride of potassium is formed, and the metallic base of the alumina combines with the mercury. The amalgam quickly oxidises by exposure to air; but being heated out of contact with the atmosphere, the mercury is [p475] volatilized, and a metallic button is left, having the colour and splendour of tin. A fuller account of the researches of M. Oersted on this subject is expected.—Hensmann’s _Repertoire—Phil. Mag. N. S._ ii.

18. _Mutual Action of Lime and Litharge_.—M. Fournet heated a mixture consisting of 7.12 parts of calcined lime, and 27.89 parts of litharge, very strongly; a coherent mass was obtained, which, pulverized and digested in water, gave, when filtered, a perfectly clear and colourless liquor, which, when treated with sulphuretted hydrogen, threw down an abundant black precipitate: hence oxide of lead is rendered soluble in water by means of lime.—_Ann. des Mines_, i. 538.

19. _New Chloride of Manganese discovered by_ M. J. Dumas.—This chloride corresponds in proportions to the manganesic acid, and in contact with water, produces muriatic and manganesic acids. It is easily obtained by putting a solution of manganesic acid into contact with concentrated sulphuric acid, and fused common salt. Water and the new chloride are formed; the former is retained by the acid, the latter volatilizes in a gaseous form. The body does not, however, appear to constitute a permanent gas[132], for though, when produced, it appears as an elastic fluid having a cupreous or greenish tint, yet when passed into a tube, cooled to 5° or 4° Fahrenheit, it condenses into a liquid of a brownish green colour.

When the perchloride is produced in a large tube, its vapour gradually displaces the air present, and the tube becomes filled with it; if it then be poured into a jar with moistened sides, the colour of the gas changes as it comes into contact with the moist air; a thick smoke of a fine rose colour appears; and the sides of the vessel acquire a deep purple colour due to the manganesic acid formed. The water thus coloured is abundantly precipitated by nitrate of silver, and, acted upon by a solution of potash, produces all the changes of the mineral chamelion.

The most simple process for the preparation of this body appears to be to form a common green chamelion, to convert it into red chamelion by sulphuric acid, and to evaporate the solution, which will give a residue consisting of sulphate and manganesate of potash. This mixture, acted upon by concentrated sulphuric acid, produces the solution of manganesic acid, into which the common salt is to be thrown in small pieces, until the vapours which rise are colourless; the latter effect is a sign that all the manganesic acid is decomposed, and that muriatic acid only is produced.

An analogous compound is formed when a fluoride is used in place of the common salt. But all attempts as yet made to collect a sufficient quantity for examination have failed; the chloride, on the contrary, is easily formed and examined, although it is not so easy to preserve it.—_Annales de Chimie_, xxxvi. 81. [p476]

FOOTNOTE:

[132] Query, what is a permanent gas?—ED.

20. _Preparation of pure Oxide of Zinc, by_ M. Hermann.—It is by no means easy to obtain this substance perfectly pure; the following is M. Hermann’s process: Oxide of zinc, or metallic zinc, is to be dissolved in excess of sulphuric acid, and the solution being filtered, sulphuretted hydrogen is to be passed through, so long as a brown or yellow precipitate is formed. Cadmium, lead, or copper, being thus separated, and the solution filtered, it is to be treated with solution of the chloride of lime, (bleaching powder,) by which the iron and manganese will be separated. The solution, again filtered, is then to be crystallized in porcelain vessels, by which sulphate of lime is rejected, and a mother liquor separated, which usually contains cobalt and nickel. The crystals of sulphate of zinc are to be dissolved in as small a quantity of cold water as possible, and the sulphate of lime filtered out; then the solution, being rendered more dilute, is to be decomposed by carbonate of soda in slight excess, and the precipitate well washed, dried, and heated to redness: it is then a perfectly pure and beautifully white oxide.—_Bull. Univ._ A. viii. 263.

21. _Deuto-Sulphuret of Cobalt_.—Mix finely divided oxide of cobalt with three times its weight of sulphur, and heat to very dull redness, until no more sulphur sublimes. The deuto-sulphuret consists of 100 cobalt + 109 sulphur; it is black; is reduced to gray proto-sulphuret by a strong heat.—_Sitterberg_.

22. _Separation of Bismuth from Mercury by Potassium_.—M. Serullas has pointed a striking instance of the separation of bismuth from mercury. He says a twelve hundred thousandth, and even less of bismuth, when dissolved in mercury, may be separated and rendered visible by the addition of a certain quantity of the amalgam of potassium and a little water. A black powder is observed to rise from the substance of the metal, and is a mixture of bismuth and mercury in a very divided state; it rises to the surface or adheres to the vessels.

Copper, lead, tin, and silver, are equally separated, but not so promptly, or so evidently to the eye as bismuth; for they are not associated with divided mercury, at the time of their separation, like the latter: with bismuth a mere atom is rendered visible, and M. Serullas thinks that chemistry does not present a more delicate test than the amalgam of potassium for bismuth in mercury.—_Annales de Chimie_, xxxiv. 195.

23. _Sulphuret of Arsenic proportionate in Composition to Arsenic Acid_.—M. Pfaff acted upon arsenious acid by nitro-muriatic acid, and obtained a pure arsenic acid soluble in water, and deliquescent in the air. This, dissolved in 40 parts of water, had a current of sulphuretted hydrogen passed through it, which instantly produced a yellow orange precipitate of a pulverulent form, continuing identical in composition, until no further precipitate was [p477] occasioned. The fluid was then perfectly free from arsenic. The precipitate was pure sulphuret of arsenic, soluble in ammonia when slightly heated, and composed of equal parts of sulphur and the metal.

M. Pfaff further says that arsenic acid may be separated from its combinations with bases, by dissolving the arseniates in nitric acid, and passing sulphuretted hydrogen through the solution; an abundant precipitate of sulphuret of arsenic is formed, containing no trace of the base of the arseniate decomposed.—_Bull. Univ._ A. viii. 256.

24. _New Double Chromates_.—Mr. Stokes has obtained several new salts, by mixing chromate of potash with metallic sulphates. Chromate of potash, mixed with sulphate of zinc, gave a precipitate of chromate of zinc; and the mother liquor, by concentration, yielded certain yellow crystals in the form of a flat rhombic prism, which Dr. Thomson had mistaken for impure sulphate of zinc, but which Mr. Stokes recognised as a new compound: 50 grains gave 18.33 sulphuric acid; 0.18 chromic acid; 9.87 oxide of zinc; 8.91 potash; 12.6 water: 0.11 loss.

Chromate of potash and sulphate of nickel were mixed in atomic proportions, and the solutions heated; after the chromate of nickel was separated, they were evaporated to dryness. The residuum, digested in water, was filtered, and the deep red solution obtained upon cooling, yielded grass green crystals in the form of oblique rhombic prisms; 50 grains of these, when analysed, gave 12.26 sulphuric acid; 0.978 chromic acid; 8.2 oxide of nickel; 9.862 potash; 12.7 water.

A similar salt may be obtained by mixing chromate of potash and sulphate of copper. It is of a light green colour, and has precisely the same form as the salts already described. In every case crystals of bichromate of potash were produced in the second crop crystals.—_Phil. Mag. N. S._ ii. 427.

25. _Dobereiner’s finely divided Platina_.—The following is M. Dobereiner’s process for obtaining finely divided platina, fit for the performance of the experiment which he first made on the combination of oxygen and hydrogen, at common temperatures. Mix muriate of platina with a solution of neutral tartrate of soda in a glass tube, half or three-quarters of an inch in diameter, and twenty or thirty inches in length, and apply heat until the fluid becomes slightly turbid; afterwards expose it for several days to the sun’s rays. The greater part of the platina will separate from the solution, and be deposited in minute laminæ, of a greyish black colour on the sides of the glass; the tube and its contents are to be put into a glass vessel containing water, and it is to be filled with hydrogen gas; the platina becomes almost immediately white and shining like silver, and may then be readily detached from the glass. During the reduction of the platina the tartaric acid is partly converted into carbonic and formic acids. “As the inflammation [p478] of the hydrogen,” it is said, “is caused by abstracting a portion of the caloric from the oxygen, effected by the platina, the smaller the laminæ of the metal are, the more readily is the incandescence produced.” Spongy platina for the lamps for instantaneous light, is prepared of great power, by moistening the muriate of ammonia and platina with a concentrated solution of ammonia; the paste formed is to be heated to redness in an earthen or platina crucible.—_Hensman’s Repertoire—Phil. Mag. N. S._ ii. 388.

26. _New Metals_.—Professor Osann, of Dorpat, is said to have discovered three new metals in the crude platina, obtained from the Uralian mountains. One, which has occurred only in one specimen of the ore, resembles osmium in some of its compounds. The second forms white acicular crystals from a nitro-muriatic acid solution; these, when heated, being softened and reduced. The third is insoluble in nitro-muriatic acid, and, by a particular process yields a dark green-coloured oxide. The account as yet given of these substances is not precise enough to allow of any judgment respecting their claim to the character of new metals.

27. _Analysis of Porcelain, Pottery, &c., by_ M. Berthier.—Earthenware manufactures are divided by M. Berthier into three kinds, those of 1. Porcelain; of 2. Pottery; and of 3. Crucibles, Bricks, &c. The following is the composition of certain porcelains:

PORCELAIN.

Sèvres. English. Piedmont. Tournay. (i.) (ii.) (iii.) (iv.) Silica 0.596 0.770 0.600 0.753 Alumina 0.350 0.086 0.090 0.082 Potash 0.018 .. .. 0.059 Soda .. .. .. 0.059 Lime 0.024 0.012 0.016 0.100 Magnesia 0.070 0.152 .. Water 0.008 0.056 0.136 0.006 ----- ----- ----- ----- 0.996 0.994 0.994 1.000

(i.) Sèvres service—Paste strongly heated. It is formed from 0.63 washed kaolin of Limoges; 0.105 quartz sand; 0.052 Bougeval chalk; 0.21 of the fine sand obtained from kaolin by washing, and which is a mixture of quartz and felspar. The glaze of this ware is made of a rock composed of quartz and feldspar. When reduced to a fine powder, it is found to be composed of silica .730, alumine 162, potash 84, water 6: it fuses into a perfectly transparent and colourless glass.

(ii.) Worcester porcelain—Paste taken from the workshops, unbaked.

(iii.) Porcelain of Piedmont—Paste dried. The base of this manufacture is the _magnesite_ of Baldissero.

(iv.) Porcelain of Tournay—Clay, chalk, and soda enter into its composition. It is very fusible, but not very fragile. [p479]

POTTERY.

Nevers. Paris. Gergovia. (i.) (ii.) (iii.) Silica 0.572 0.541 0.544 Alumina 0.124 0.127 0.220 Lime 0.226 0.063 0.064 Oxide of Iron 0.066 0.070 0.098 Magnesia .. 0.024 0.038 Water .. 0.173 0.020 ----- ----- ----- 0.988 0.998 0.984

(i.) Earthenware of Nevers—Paste of a pale red. Made of a marle occurring close to the town; the glaze is a white enamel, containing both tin and lead.

(ii.) Paste of the brown earthenware made by M. Husson at Paris. The biscuit is red, but is covered by a brown glaze, coloured by oxide of manganese.

(iii.) Red earthenware resembling the Etruscan, and found in the ruins of Gergovia near Clermont.

CRUCIBLES, &C.

St.
Hessian. Paris. English. Etienne.
(i.) (ii.) (iii.) (iv.)
Silica 0.709 0.646 0.637 0.652
Alumina 0.248 0.344 0.207 0.250
Oxide of Iron 0.038 0.010 0.040 0.072
Magnesia trace .. .. trace
Water .. .. 0.103 ..
----- ----- ----- -----
0.995 1.000 0.987 0.974

Le
Nemours. Bohemia. Creusot.
(v.) (vi.) (vii.)
Silica 0.674 0.680 0.680
Alumina 0.320 0.290 0.280
Oxide of Iron 0.008 0.022 0.020
Magnesia trace 0.005 trace
Water .. .. 0.010
----- ----- -----
1.002 0.997 0.990

(i.) Hessian crucibles—formed of a clay very aluminous, with which siliceous sand is mixed. They sustain rapid changes of temperature without fracture, but cannot retain fused litharge very long together, and have too coarse a grain for many purposes.

(ii.) Paris crucibles, manufactured by Beaufaye—they are made from the clay of Andennes, near Namur; part of the material being baked and coarsely powdered, and the rest in its natural state: no sand is mixed with it, and the inner surface of the vessels is finished with a thin coat of the unbaked material. They are said to be more refractory than the Hessian vessels, not more liable to fly by change of temperature, and more retentive of litharge.

(iii.) Fragment of an unbaked crucible prepared for an English cast-steel work.

(iv.) Paste with which the crucibles are made for the steel works of Berardière, near St. Etienne.

(v.) Fragment of a used crucible from the glass works of Bagneaux, near Nemours; it had been made from the clay of Forges (Seine Inférieure).

(vi.) A used crucible from a Bohemian glass-house.

(vii.) Bricks with which the blast furnaces at Creusot are [p480] constructed; they are made of a mixture of baked and unbaked clay.—_Annales de Chimie_, i. 469.

28. _On the Composition of simple Alimentary Substances, by_ Dr. Prout.—It is well known that Dr. Prout has of late years devoted that portion of his attention which he gives to chemistry, exclusively to the consideration of organized substances, with the important object of making the knowledge he might obtain subservient to the study of physiology and pathology; and during the last session of the Royal Society, a paper by this philosopher was read, containing many important and apparently accurate results relative to the particular subjects which he has pursued; some account of which we are desirous of giving in this place.

Dr. Prout’s first object was to devise, if possible, an unexceptionable mode of determining the proportions of the three or four principles, which, with few exceptions, form organic bodies; and after numerous trials, he adopted a method founded upon the following well known principles. When an organic product, containing three elements, hydrogen, carbon, and oxygen, is burnt in oxygen gas, one of three things must happen: i. The original bulk of oxygen gas may remain the same, in which case the hydrogen and oxygen in the substance must exist in it in the same proportions in which they exist in water; or, ii. The original bulk of the oxygen may be increased, in which case the oxygen must exist in the substance in a greater proportion than it exists in water; or, iii. The original bulk of the oxygen gas may be diminished; in which case the hydrogen must predominate. Hence it is obvious, that, in the first of these cases, the composition of a substance may be determined, by simply ascertaining the quantity of carbonic acid gas yielded by a known quantity of it; while, in the other two, the same can be readily ascertained by means of the same data, and by noting the excess or diminution of the original bulk of the oxygen gas employed.

The apparatus consists of two inverted glass syphons which act the part of gasometers; these are connected when required, by a small green glass tube, in which the substance is to be decomposed and burnt: the syphons are very carefully gradated; so that the quantity of gas in them can be accurately estimated; and are supplied with cocks both above and below, so that they can be filled with mercury, the mercury drawn off and gas introduced, the gas transferred through the green glass tube, or the contents retained in an undisturbed state, with the utmost readiness and ease. The substance to be decomposed, may be put into a platina tray, and introduced alone into the green glass tube, and being there heated by a spirit lamp, be burnt in the gas passing over it; or it may be mixed with pure siliceous sand; or, what is most generally preferable, be mixed with peroxide of copper, which is always left, in consequence of the excess of oxygen gas used, in the state in which it was introduced. After the experiment the volume of gas is easily [p481] corrected for pressure, and if necessary for temperature, and the carbonic acid ascertained by the removal and analysis of a portion. No correction is required for moisture, the gas always being used saturated with water.

Dr. Prout considers the principal alimentary substances as reducible to three great classes, the _saccharine_, the _oily_, and the _albuminous_; and his paper relates to the first of these. This, with certain exceptions, includes the substances in which, according to MM. Gay Lussac and Thenard, the oxygen and hydrogen are in the same proportion as in water. Such substances are principally derived from the vegetable kingdom, and being at the same time _alimentary_, Dr. Prout uses the terms _saccharine principle_ and _vegetable aliment_ as synonymous.

The following tables show some of Dr. Prout’s results with several substances, extreme care having been taken in every case to obtain the bodies pure, and new processes often resorted to for that purpose.

SUGAR.

Carbon. Water. Pure sugar-candy 42.85 57.15 Impure sugar-candy 41.5 to 42.5 58.5 to 57.5 East India sugar-candy 41.9 58.1 English refined sugar 41.5 to 42.5 58.5 to 57.5 East India refined sugar 42.2 57.8 Maple sugar 42.1 57.9 Beet root sugar 42.1 57.9 East India moist sugar 40.88 59.12 Sugar of diabetic urine 36. to 40? 64. to 60? Sugar of Narbonne honey 36.36 63.63 Sugar from starch 36.2 63.8

AMYLACEOUS PRINCIPLE.

Carbon. Water.
Fine wheat starch 37.5 62.5
" dried (i.) 42.8 57.2
" highly dried (ii.) 44 56
Arrow root 36.4 63.6
" dried (iii.) 42.8 57.2
" highly dried (iv.) 44.4 55.6

(i.) Dried between 200° and 212° for twenty hours, lost 12.5 per cent.

(ii.) Part of the former, dried between 300° and 350° for six hours, lost 2.3 per cent.

(iii.) Dried as (i.), lost 15 percent.

(iv.) Part of the last, heated to 212° for six hours longer, lost 3.2 per cent. more.

LIGNIN, OR WOODY FIBRE,

Obtained by rasping wood, and then pulverising it in a mortar; boiling the impalpable powder in water till nothing more was [p482] removed, then in alcohol; again in water, and dried in the air till they ceased to lose weight.

Carbon. Water.
From box 42.7 57.3
" dried (i.) 50. 50.
From willow 42.6 57.4
" dried (i.) 49.8 50.2

(i.) Dried at 212° for six hours, afterwards between 300° and 350° for six hours. That from box lost 14.6, that from willow 14.4 per cent.

Acetic acid 47.05 52.95

Sugar of milk 40. 60. Manna sugar 38.7 61.3 Gum arabic 36.3 63.7 " dried (i.) 41.4 58.6

(i.) Dried between 200° and 212° for twenty hours, lost 12.4 per cent. The same gum further heated to between 300° and 350° for six hours, lost only 2.6 per cent., and had become deep brown.

Vegetable Acids. Carbon. Water. Oxygen.

Oxalic acid 19.04 42.85 38.11 Citric acid 34.28 42.85 22.87 Tartaric acid 32.00 36.00 32.00 Malic acid 40.68 45.76 13.56 Saclactic acid 33.33 44.44 22.22

29. _Preparation of Sulphate of Quinia and Kinic Acid, without the use of Alcohol_.—The following is the process of MM. Henry and Plisson: About two pounds of bark are to be coarsely powdered and boiled with water, acidulated with sulphuric acid in the usual manner. When the hot liquors are cleared, recently prepared and moist hydrate of lead is to be added until the fluid is neutral, and has acquired a faint yellow colour; this must be done carefully, lest too much hydrate of lead be added. As the decoloration of the decoction is necessary, the liquid, if it remains turbid until the next morning, must have a little more hydrate added and be re-filtered, but the operation is rarely subject to this inconvenience, being usually finished in a few hours. The yellow liquid contains a little kinate of lead, much kinate of lime, kinate of quinia or cinchonia, a little colouring matter, and traces of other substances. The washed deposite consists of colouring matter, combined with oxide of lead, sulphate of lead, and a portion of free quinia; contains no sub-kinate of lead.

The lead, dissolved in the fluid, is to be separated by a few drops of sulphuric acid, or a small current of sulphuretted hydrogen, and the filtered liquid is to be precipitated by adding caustic lime, previously mixed into a thin paste with water, until the earth is in very slight excess; in this manner the quinia is precipitated. The addition of sulphuric acid readily converts this quinia into sulphate, [p483] which may be obtained in very white and silky crystals. The fluid left after the separation of the quinia, contains a kinate of lime almost pure. Being evaporated until of the consistence of syrup, it readily crystallizes in a mass, which may then be purified by recrystallization. The kinate of lime may be precipitated by means of alcohol, and then be crystallized after solution in water or diluted alcohol; or, by adding oxalic acid drop by drop, according to the directions of M. Vauquelin, the lime may be separated and kinic acid obtained. Two thirds of the quinia or cinchonia in a specimen of bark may be thus separated, and with such facility as to offer a ready test of the presence of these alkalies in any wood or bark submitted to examination.—_Ann. de Chimie_, xxxv., 166.

30. _Pure Narcotine prepared_.—The following process is that practised by Mr. Carpenter. Digest one ounce of coarsely powdered opium in one pint of ether for ten days, frequently submitting it to ebullition in a water bath; separate the ether and add fresh portions until the opium is exhausted; place the ethereal solution in a wide-mouthed bottle, and, covering the mouth with bibulous paper, allow the ether to evaporate spontaneously, but slowly; as the fluid diminishes, it leaves the sides of the bottle coated with crystals of narcotine; as the solution becomes more dense, the crystals enlarge and accumulate, and the bottom of the vessel is covered with large transparent crystals, accompanied with a brown viscid liquor and extract, which contains an acid resin, caoutchouc, &c. Separate these substances and wash the crystals in successive portions of cold ether to remove the extract; then dissolve them in warm ether, and evaporate slowly as before; beautiful snow white crystals of pure narcotine will be obtained: those on the sides of the vessel assume plumose and arborescent forms; they enlarge as the solution becomes more concentrated, and the bottom of the bottle becomes covered with pure narcotine, assuming the rhomboidal prismatic form with some modifications of maccled crystals. The crystals towards the bottom are transparent, but the most minute at the top are opaque and snow white. By picking out the largest and most regular crystals, again dissolving and evaporating, and repeating the same process, each time selecting the largest and best crystals, some were obtained the eighth of an inch in diameter, and still larger might be produced by similar operations.—_Silliman’s Jour._, xiii. 27.

31. _Uncertain Nature of Jalapia_.—Relative to Mr. Hume’s supposed vegeto-alkali _Jalapia_, M. Pelletier says it is nothing more than a mixture of sulphate of lime and sulphate of ammonia.—_Jour. de Pharmacie_.

32. _Preparation of pure Mellitic Acid, by_ M. Wöhler.—Concentrated solution of carbonate of ammonia was poured upon finely pulverised mellite, and boiled until the excess of ammonia was [p484] dissipated; the solution was filtered and left to crystallize. The pure crystals, being dissolved in water, were precipitated by acetate of lead, and the mellitate of lead, after being well washed was decomposed by sulphuretted hydrogen; being filtered, the solution was evaporated to dryness, during which the mellitic acid precipitated as a white powder; being dissolved in cold alcohol, and left to evaporate spontaneously, the acid was obtained in acicular crystals. In this state it is very acid, unaltered by air, very soluble in water and alcohol, and sustains a considerable heat without change; it does not fuze, but ultimately sublimes, though probably not without decomposition. When boiled for a considerable time with alcohol, it undergoes a peculiar change, and occasions the production of a new acid substance, resembling the benzoic acid.

33. _On a New Acid existing in Iceland Moss_.—The reddish purple colour which is produced by adding a decoction of Iceland moss to per-salts of iron, has been attributed to the presence of gallic acid, but is found by M. Pfaff to be occasioned by a new acid body which may be separated in the following manner. A pound of the lichen cut small is to be macerated in solution of carbonate of potassa, until all that is soluble is separated; the above quantity will neutralize two gros[133] of the carbonate. The filtered liquor is to be precipitated by acetate of lead, and the brown precipitate produced, when well washed, is to be diffused through water, and sulphuretted hydrogen passed through it until all the lead is separated. The filtered liquor is acid, and by spontaneous evaporation, yields dendritic crystals. The crystals, when heated, carbonize, but produce no odour like that of tartaric acid, and lime is left. If they be dissolved and acted upon by alkaline carbonates, carbonate of lime is thrown down, and alkaline salts, containing the new acid, are produced.

The potash salt crystallizes in quadrilateral prisms, needles or plates, and is not deliquescent. The soda salt has similar characters, and the ammonia salt crystallizes in needles. These salts abundantly precipitate the acetate and muriate of iron of a red brown colour; they precipitate sulphate and nitrate of zinc white; muriate of manganese slightly of a clear brown colour; barytic and strontian salts abundantly white; being mixed with strong solutions of muriate or acetate of lime, they gradually produce an acicular crystalline white precipitate; acetate of silver yields an abundant white precipitate, which does not change colour in less than twenty-four hours: they do not precipitate salts of glucina, magnesia, alumine, uranium, nickel, copper, cobalt, gold or platina. This substance has been named the lichenic acid, and is distinguished from boletic acid by the different character of its vapour, and by forming an insoluble salt with baryta.—_Bull. Univ._ A. viii. 270.

FOOTNOTE:

[133] About one hundred and twenty grains.