the jet extends into the combustion tube sometimes cracking it, and otherwise, without this issue, causing the loss of the whole determination.

This catastrophe is especially to be feared toward the conclusion of the combustion, when little except pure ammonia occupies the interior of the tube. MM. Varrentrap and Will suggested the mixture of sugar or tartaric acid with the body to be analyzed, that other gases in quantity might be furnished and the ammonia thus diluted. The difficulty to some extent still remained, and gave rise to Schlossberger's apparatus. Fig. 1.-Varrentrapp and Will's Apparatus, Fig. 2.-Schlossberger's Apparatus,

It consisted of two little flasks, of the size used in alkalimetry by Fresenius and Will, connected by tube and corks, and so disposed as to admit air from without, in the event of condensation, without the possibility of the acid ascending into the combustion tube. This improvement most effectually removed all liability to danger.

It had however two objections:-complication and cork surfaces. It is composed of seven pieces, while the apparatus of MM. Varrentrap and Will consists of but one.

To unite the safety of the former with the simplicity of the latter, was a great desideratum.

An examination of the conditions of the problem, renders its solution easy.

The starting back of the acid follows an absorption more rapid than the evolution. The fluid that had been driven forward into the second and third bulbs, slowly returns toward the first. As the acid enters the bulb nearest the combustion tubes, the sudden expansion of its surface occasions such rapid absorption that a partial vacuum is produced. The liquid comes in so fast, that with the rush of air and vapor into the condensation tube, some of the acid is carried with it.

The causes of the difficulty are the too rapid increase of absorbing surface, and the smallness of the bulb. These are removed in the Fig. 3.-Improvement upon Fig. 1.

slight modification of the apparatus represented in fig. 3. Its use has realized all the expectations entertained. It is entirely safe.

Cambridge Laboratory, May, 1847.

4. On a quick Method of determining the quantity of Nitrogen in Organic Substances; by EUG. PELIGOT, (Comptes Rendus, March, 1847.)-The method of Varrentrapp and Will was considered a great improvement in the determination of nitrogen, particularly on account of the saving of time, &c. But this process although requiring only a short combustion, needs a prolonged manipulation of the platinum salt, and is liable to several species of error.

The method of Peligot is a simple alteration of that of Varrentrapp and Will. The combustion is performed in the same manner, but the ammonia is condensed by a known quantity (by volume or weight) of sulphuric acid. After the combustion, this acid is transferred to a cylindrical vessel, the washings added, and the strength of the acid determined by the volumetric method. The difference between this and the original strength gives the quantity of acid saturated by the ammonia, and consequently the ammonia.

For this last determination, the author prefers the solution of caustic lime in syrup. This solution preserved in close vessels undergoes no change, and even after absorbing carbonic acid from the air, it needs only a filtration to fit it for use. The strength of the alkaline solution must be previously ascertained by the usual methods.

The results are accurate an analysis of oxamide gave 31.3 per cent. nitrogen, theory requiring 31-7. By this method a determination of nitrogen may be made in less than half an hour, with an accuracy at least equal to that obtained by the usual methods which require never less than three hours.

M. Peligot considers this method peculiarly useful in the case of physiological investigations, as the determinations, being useless unless comparative and therefore numerous, may be multiplied almost without trouble or expense. G. C. SCHAEffer.

5. Preparation of Sulphocyanid of Ammonium; by J. LIEBIG, (Liebig's Annalen, Jan., 1847.)-A small quantity of sulphuret of ammonium in the presence of excess of sulphur produces the unlimited conversion of cyanid of ammonium into sulpho-cyanid-hence the following process: 2 oz. sol. caustic ammonia, sp. gr. 0.95, are saturated into sulphuretted hydrogen, and then mixed with 6 oz. of the same solution of ammonia; 2 oz. flowers of sulphur are next added, and then the product of the distillation of 6 oz. prussiate of potash, 3 oz. sulphuric acid and 18 oz. water. The mixture is digested in the water bath until the sulphur is no longer acted upon and the liquid becomes yellow; it is then boiled till the sulphuret of ammonia is driven off and the liquid has again become colorless. The excess of sulphur being removed, the liquid yields on evaporation over 3 oz. pure white sulphocyanid, which may be used as a reagent instead of the sulphocyanid of potassium.

This reaction of prussic acid with the higher sulphurets of ainmonium affords a very good test for the acid, as the sulphocyanides and persalts of iron are more delicate tests for each other than the component cyanides and iron salts forming prussian and other blues. G. C. S.

6. On the Decomposition of Nitrite of Ammonia; by E. MILLON, (Ann. de Chem. et de Phys., Feb., 1847.)-Heat decomposes the solution of nitrite of ammonia, water being formed and nitrogen given off; but if a drop of caustic ammonia is added to some of the solution in a

thin glass tube, it may be boiled for hours without decomposition. Acids produce the contrary effect, causing the immediate destruction of the nitrite.

The author proposes the following easy process for nitrate of ammonia. An excess of caustic ammonia in a platinum crucible is placed in a cooling mixture. Into this is to be passed very gradually the nitrous vapor, from the dry distillation of nitrate of lead. The solution must be evaporated in an atmosphere of ammoniacal gas, over lime. The decomposition by sulphur, has been previously noticed by Pelouze. G. C. S.

7. On a new Mode of estimating the Nitrates, and particularly Nitre ; by J. PELOUZE, (Comptes Rendus, Feb., 1847.)-The solubility of all the nitrates preventing any application of the usual methods, and yet the large quantity of nitre consumed annually in the manufacture of gunpowder requiring some mode of determination approaching accuracy, many ingenious processes have been devised, and of these a very complete history is given in the first part of the paper.

A method has been recently proposed by M. Gossart, which consists in mixing the salt with sulphuric acid and decomposing it by a normal solution of protosulphate of iron-the completion of this action being determined by ferridcyanid of potassium, for when this indicates the presence of protoxyd of iron, it is known that all the nitre has been consumed. The quantity of solution used, gives by a simple calculation the quantity of nitric acid or nitre.

M. Pelouze considers the process as original with M. Gossart, and happy in its invention. Certain difficulties however, have led to improvements by Pelouze, which seem to give the method a high degree of accuracy. He first determined the quantity of pure nitrate of potash requisite to peroxydize a known weight of pure iron, (piano wire being selected as the purest and most convenient.) 2 grms. of wire dissolved in an excess of hydrochloric acid, on an average required 1·216 grms. of nitrate. This decomposition involves 6 equivs. iron and 1 equiv. nitrate, the acid being decomposed into deutoxyd of nitrogen, which is given off, and into oxygen, which produces the perchlorination of the iron. Thus :

6FeCl.+NO,KO+4HC|=4HO+KCl+NO2+3(FeCl ̧). (This reaction is proposed as an excellent method of preparing the deutoxyd of nitrogen.) As the presence of chlorids and sulphates in the crude nitre does not interfere, it is only necessary to operate upon 2 grms. iron and 1.216 of nitre, and by a standard solution of chameleon mineral (permanganate of potash), ascertain how much iron remains to be peroxydized. The method of preparing and using this last solution will be found in this Journal for September, 1846, p. 257.

In an actual analysis, 2 grms. of wire are placed in a suitable flask with 80 to 100 grms. strong hydrochloric acid; the flask is closed by a cork having a fine tube in it. After dissolving the iron with a gentle heat, 1216 grms. of the nitre to be examined, are added, the flask closed and the whole boiled. As soon as the gas has escaped, and the brown color disappears, the liquid becomes clear and yellow-after boiling five or six minutes it is poured into a quart flask, the wash water added and water to fill the vessel. The normal solution of permanganate is then applied until after agitation a faint rosey hue remains.

In the first part of the process the continual escape of vapor and gas prevents the entrance of the oxygen of the air-after this there is no further danger, as iron in a strongly acid solution is peroxidized with much difficulty, even by exposure to the air.

In general it is best to use the nitrate in a solid form-but to prevent variations in small samples of crude nitre, it is best to dissolve a large quantity and take the proper proportion of the solution for analysis. Of course this process only indicates the quantity of nitrate and does not show the adulteration of nitre by nitrate of soda. G. C. S.

8. On the Composition of Quinoidine; by J. LIEBIG, (Liebig's Annalen.) Quinoidine has been considered by some chemists as a mixture of quinine and cinchonine with resin, which prevents crystallization. Others regard it as a distinct alkaloid. Liebig however found it to yield on distillation as much quinoleine as pure quinine, and on analysis it proved to have the same composition and atomic weight. Quinoidine is therefore nothing more than amorphous quinine. G. C. S.

9. On the Fat Acids of the Oil of Ben; by P. WALTER, (Comptes Rendus, June, 1846.)-The oil of ben is the produce of the Moringa aptera, and was formerly much used in perfumery as a vehicle for odors, being in itself perfectly scentless. Walter found on examination no volatile acid, but stearic, margaric, and two new fat acids. The one, Benic acid, is very small in quantity, its formula C30H300, standing between nysistic and ethalic acids. Melting point about 127°. Benic ether is a readily fusible solid.

4

The other acid is named from the plant, Moringic acid-its formula C30H2304. This is a colorless or yellowish oil, solidifying at 32°, soluble in alcohol, and decomposed by sulphuric acid when heated with it.

G. C. S.

10. On the Fermentation of Tartaric Acid; by I. NICKLES, (Comptes Rendus, Aug., 1846.)-Noeldner described as a peculiar acid that which results from the fermentation of tartrate of lime containing impurities. Berzelius pronounced this acid, called the pseudo-acetic by Noeldner, to be a mixture of acetic and butyric acids.

M. Nickles does not decide upon this point, but states that an acid is formed containing the elements of acetic and butyric acids, having the composition CH04. This would be isomeric with Gottlieb's metacetonic acid.

The experiments given by the author are not quite conclusive as to the separate existence of this acid.

G. C. S.

11. On the Preparation of Ferridcyanid of Potassium; by A. and C. WALTER, (Buchn. Rep., xliv, p. 42; Chem. Gaz., June 1, 1847.)— Yellow prussiate of potash is boiled with 12 to 15 parts of water, and while boiling, good chlorid of lime added until a filtered sample appears red, or no longer yields a blue precipitate with persalts of iron. It is then quickly filtered, a little carbonate of potash added to the solution until it has a faintly alkaline reaction, and then evaporated to crystallization; the crystals obtained are purified by recrystallization.

12. On the Method of separating Cobalt from Manganese, proposed by Barreswil; by A. STRECKER, (Liebig's Annalen, Feb., 1847; Chem. Gaz., May 15, 1847.)-A short time since M. Barres wil* proposed a

* See this Journal, vol. ii, ii Series, p. 260.

very simple method of separating these two metals, by adding carbonate of baryta to the solution containing them, and then passing sulphuretted hydrogen into it. The author, before employing it, wished to ascertain whether in reality no manganese would be precipitated, as stated by M. Barreswil, and mixed for this purpose solutions of the protochlorid and of the protosulphate of manganese with pure carbonate of baryta, and passed sulphuretted hydrogen into them. It was found that nearly the whole of the manganese was precipitated, and the filtered alkaline liquid became turbid on heating to boiling, and contained now not a trace of manganese. This is readily explained by the behavior of carbonate of baryta towards sulphuretted hydrogen. When a current of this gas is passed into water containing carbonate of baryta in suspension, a portion of it is decomposed in the same way as the alkaline carbonates, and the liquid contains a considerable quantity of baryta in solution, partly in the form of carbonate dissolved in carbonic acid, partly as hydrosulphuret of barium and hyposulphite of baryta. The very alkaline liquid is rendered turbid by boiling, with separation of carbonate of baryta, and on evaporation to half its volume constantly disengages sulphuretted hydrogen; upon the addition of muriatic acid, this gas and carbonic acid escape, and the liquid is rendered turbid by sulphur; sulphuric acid indicates the presence of a large amount of barytic salts. It is to be hoped that when M. Barreswil next imagines a method, he will test its correctness before publishing it.

13. Occurrence of Arsenic in Vinegar, (Journ. de Chim. Méd., ii, p. 334; Chem. Gaz., June 1, 1847, p. 213.)-M. DESCHAMPS found, on preparing pure acetic acid from wood-vinegar, that the latter contained arsenic, which he ascribes to arseniferous sulphuric acid having been used in the manufacture of the pyroligneous acid. As wine-vinegar is frequently strengthened with pyroligneous acid, M. Chevalier was induced to examine several samples of ordinary vinegar, and found some of them to contain very perceptible quantities of arsenic.

14. Mode of detecting the Adulteration of Olive Oil with Rape or Poppy Oil; by M. DIESEL, (Archiv. de Pharm. in Chem. Gaz.)— Common nitric acid colors pure olive oil green; a mixture of olive and rape oil produces a yellowish grey color, and with poppy oil a yellow. ish white. After about twelve hours, pure olive oil is itself colored; the determination must therefore be made before that time has elapsed. G. C. S.

15. On a Ready Method of determining the Amount of Nicotine in Tobacco; by M. SCHLOESING, (Comptes Rendus, Dec., 1846.)-Ten grammes of tobacco are to be exhausted with ammoniacal ether, in an apparatus for continued distillation, the ammonia expelled by boiling, the solution decanted and the ether evaporated. The amount of nicotine is then determined by sulphuric acid of known strength, according to the usual alkalimetric method.

This process was found to give results closely agreeing with the amount determined by a careful separation of nicotine.

Tobacco containing a large per cent. of nicotine seems to be that generally preferred for the manufacture of snuff. The snuff itself contains but about one-third of this nicotine, the remainder having been destroyed by the fermentation. This increases the quantity of ammo