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The sugar employed by the authors of the process to prevent the too rapid absorption of the ammonia by the hydrochloric acid, during the combustion of substances very rich in azote, also sugar burnt in the ordinary apparatus with the alkaline mixture, have always afforded me quantities of ammoniacal chloride of platinum, which, as will be seen, are by no means unimportant.

The ammonia obtained under these circumstances, can only be ascribed to the azote contained in the tube, and not the re-agents employed.

The mixture which I used was prepared with all the care possible, by calcining at a red heat in an earthen crucible, two parts of slaked lime with an aqueous solution of one part of caustic soda recently prepared. The mass was quickly powdered, then slightly heated to drive off any moisture it might have attracted, and introduced while still hot into a stoppered bottle.

After first proving by experiment, that neither the alkaline mixture nor the chloride of platinum used in my experiments, contained any azote, I proceeded to the combustion of sugar.

1st. One gramme (15.444 grains) of sugar perfectly white, was burnt in an ordinary tube with the alkaline mixture, which, on the addition of the chloride of platinum to the hydrochloric acid, afforded very brilliant, yelow, insoluble crystals of chloride of platinum and ammonium, and which, after calcination, gave *089 gramme of metallic platinum, corresponding to .0127 gramme of azote.

2d. Two grammes of the same sugar, gave under similar circumstances, •10725 gramme of metallic platinum, corresponding to .0153 gramme of azote.

3d. One and a half gramme of sugar-candy, in fine crystals, gave •104 gramme of metallic platinum, corresponding to .0149 gramme of azote.

I also effected the combustion of stearine, and obtained ammonia from it.

The new process for the determination of azote has succeeded perfectly, in the hands of MM. Varrentrapp and Will, in a great number of cases; several other chemists have also reported favourably of it; these are facts which I am by no means disposed to doubt ; but it is important that it should be distinctly understood, that this process may lead to serious errors in operating on non-azotized substances, or even on azotized substances which are very rich in carbon, and the combustion of which is difficultly effected with the alkaline mixture.

Moreover, there exists another source of error in the employment of this process, which deserves to be mentioned. I allude to the reduction of a small quantiiy of the bichloride of platinum into protochloride under the influence of the mixture of alcohol and ether.

Faraday, in his paper on some circumstances attending the formation of ammonia, has shown that iron, zinc, and those metals,

generally, which are easily oxidized, when fused in contact with potash give rise to the formation of ammonia, even in an atmosphere of hydrogen.

I have ascertained, in fact, that at a temperature which need not be higher than 265° Fahr., iron filings and a concentrated solution of potash afford an abundant evolution of hydrogen, and at the same time the smell of ammonia becomes very sensible, even in operating with a grain of potash. But this formation of ammonia does not take place, if the operation be conducted in an atmosphere of hydrogen prepared with sulphuric acid, free from nitrous gas.

Annales de Chemie et Physique. (Phar. Journal.)

Chinova-bitter. By Dr. F. L. WINCKLER.

In preparing a large quantity of Chinova-bitter, I had occasion to study accurately the chemical properties of this bitter matter. According to the results of these experiments, the Chinova-bitter is a well-characterized acid, which not only forms with most metallic oxides amorphous compounds soluble in water, but forms also with ammonia, soda, and potash, perfectly neutral but uncrystallizable salts easily soluble in water. The solution of the ammonia salt loses the ammonia completely, either by being evaporated under moderate heat, and even by spontaneous evaporation in the air, and, on being evaporated to a state of dryness, leaves behind the Chinova-bitter as a very easily friable, enamel-like, snow-white, amorphous mass. The potash salt is to be obtained by the evaporation of the solution in a perfectly undecomposed state, and forms when dry, a mass easily friable, and rather shiny; it dissolves very copiously in water; the aqueous solution is decomposed by carbonic acid, with the deposition of unchanged Chinova-bitter.

All salts of Chinova-bitter possess a very bitter taste, fuse, when heated with a spirit lamp, and are decomposed, developing curious vapours, of a peculiar odour and white colour. If a flame be brought in contact with the melting mass, the vapours easily ignite, and the mass is burnt completely, presenting a clear, full, red, strongly sooty flame, the metals or oxides remaining behind. The combination of the oxide of silver with Chinova-bitter, which can be easily obtained by the decompositon of the neutral ammonia salt, by nitrate of silver, in the form of a white gelatinous precipitate, will dry up (even if the access of air be carefully prevented) into a blackish-grey, or nearly black, amorphous, easily friable mass. 0.2 grammes of the dry silver compound, after being burnt, left behind, according to these experiments (the results of which correspond very well with each other), at an average 0·042 grammes of silver=0043659 grammes of oxide of silver.

The per-centage composition, therefore, of the compound is,

78.1705 Chinova-bitter.
21.8295 Oxide of silver.

100: Another result had been previously obtained by the analysis of the compound of silver, which I had procured by means of nitrate of silver from a basic fluid, prepared by boiling a mixture of lime, Chinova-bitter, and water. 0.315 grammes of this compound left behind, after being burnt, 0.145 grammes of silver=0:1507 grammes of oxide of silver, which corresponds with the per-centage composition of

52:1517 Chinova-bitter.
47.8413 Oxide of silver.

100. This compound is therefore a basic one. The above may suffice as a contribution to the more accurate chemical knowledge of the Chinova-bitter. It remains to be elucidated in what relation Chinova-bitter stands to Chinova acid (Pelletier and Caventou). I have, on operating on large quantities of China nova, endeavoured in vain to find this acid, which, according to the opinion of the above chemists, does not precipitate salts of the oxides of iron, copper, or silver. In my former communications on the composition of this bark, I have stated them on the authority of Pel. letier and Caventou, my attention having been particularly directed towards the Chinova-bitter. On this account I reserve to myself a repetition of the qualitative and the quantitative analysis of the China nova; but according to what I have hitherto observed about the chemical relation of the Chinova-bitter, I might now rather designate it by the name of Chinova-bitter acid. A confirmation of the different statements on the composition of Chinova-bitter of Messrs. Buchner and Petersen may be soon looked for, as Professor Wöhler, of Göttingen, is causing the elementary analysis to be repeated, and there can be no doubt that the results will be duly published.

Pharm. Central Blatt. (Phar. Journal.)

THE BUDE AND BOCCIUS LIGHTS.

Report of Dr. A. Ure, F.R.S., Professor of Chemistry, Consulting

and Analytical Chemist, fc. &c. I HAVE carefully perused the specification of Mr. Gurney's patent, also the evidence taken before a Committee of the House of Commons on the advantages of his improvements in the lighting of that house, and I am of opinion, that the patent is perfectly good in law, as by this evidence it is clearly proved that artificial light is thus produced in greater quantities, and of a better quality, than by any other means heretofore known, and at a saving of 50 per cent. A material benefit is consequently conferred upon the public, and such as is intended to be protected by the statute, even if the patentee laid no claim to the novelty of any of the apparatus, or materials used.

This construction of the law has been borne out by many recent decisions, but more particularly in the case of Crane against Prince and others, in which judgment was given last term. In this case an action was brought for an infringement of a patent obtained for improvements in the manufacture of iron, by using anthracite coal in combination with hot blast, neither of which were new, and both of which had been previously used for that purpose, though not in conjunction. The verdict was, nevertheless, for the plaintiff, and Chief Justice Tindal, in pronouncing judgment, observed, that "if the result of a combination is either a new article, or a better article, or a cheaper article, to the public, than that produced by the old method, such a combination is an invention, or manufacture in. tended by the statute to be protected by a patent, even when the invention, or improvement, consisted in no more than the use of things already known, and acting with them in a manner already known, and producing effects already known, but producing those effects, so as to be more economically, or beneficially enjoyed by the public."

Now it appears to me that the law as thus laid down, and recognised by the judges, is equally applicable to Mr. Gurney's combination of materials for the production of light, even admitting that there were no novelty in those materials, the result (which is the material point at issue,) being the production of an article of commerce, which is more beneficially enjoyed by the public, as proved in so satisfactory a manner by the Report of this Parliamentary Committee before which I was myself examined.

I have inspected, also, the drawings and specification of the patent obtained by Gottlieb Boccius, and I have likewise examined the light recently erected opposite Northumberland House, in the Strand, known as the “Boccius Light," and I have no hesitation in pronouncing it to be a manifest piracy and barefaced imitation of Mr. Gurney's patent.

Having been originally consulted on the case of the Queen v. Bynner, whose patent for what is termed the Solar Lamp," was recently repealed by a scire facius, as defective, false, &c., I am of opinion that, if a similar course was pursued with respect to the Boccius patent, a similar result would follow. . (Signed)

ANDREW URE. 13, Charlotte-street, Bedford-square,

October 4, 1842.

XXIII.-On the rapid Detithonizing Power of certain Gases and

Vapours, and on an instantaneous means of producing Spectral appearances. By John W. DRAPER, M.D., Professor of Chemistry in the University of New York.

TAKE a bromo-iodized silver plate, expose it to the light of the sky or lamplight for a length of time sufficient to brown it sensibly and uni. formly all over. In this state, if it were placed in the vapour of mercury, it would solarize or blacken in every part. But, before mercurializing, treat it as follows. Lay upon it a fragment of glass, a piece of metal, or any other object; immerse it for a second or two in a box containing the vapour of iodine; withdraw it, remove the little object, and mercurialize forthwith; and now you will find a perfectly formed, black, spectral impression of the object, whatever it was, powerfully brought out by the mercury vapour; but on all those parts to which the iodine vapour has had access, the mercury will not adhere, but the phenomenon will take effect as though the plate had never been exposed to the light, except on those portions on which the object, whose spectral image appears, was laid.

From this it would seem that the vapour of iodine has the quality of detithonizing a surface that bas been changed by light.

The same process may be conducted so as to give a still more striking result.

Employing a prepared bromo-iodized plate as before, expose it to any uniform source of light for such a length of time that if it were mercurialized it would whiten uniformly and exhibit the aspect of an ordinary white Daguerreotype. Treat it as before, by placing on it any object, pass it into the vapour of iodine,-remove the object, and mercurialize; and now a spectral appearance of that object, of a dense white aspect, will emerge, the remainder of the plate being quite black and in the condition of the shadows of a Daguerreotype, that is, as though it had never been exposed to the Jight.

In order to obtain a clear idea of what passes under the foregoing circumstances, I made the following trial.

Upon a plate prepared and deeply tithonized, as has been said, I laid a double convex lens of about two inches focus, and exposing the plate with the lens upon it to the vapour of iodine, and then removing the lens, I mercurialized. A deep blue spectral image immerged, of less diameter than the lens, but like it of a circular form, its circumference being marked by as sharp a line as if it had been drawn by a pair of compasses. Indeed it looked as distinct and as sharp as if a blue wafer had been laid on the plate.

In several successive trials I found that the magnitude of this spectre diminished as the time of exposure to the vapour had been prolonged,

Next, I repeated the same trial, using the plate and lens as just described ; but immersing the plate in the vapour of bromine instead

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