Зображення сторінки
PDF
ePub

The preceding analyses appear to establish beyond a doubt the composition of aniline-blue; and I do not hesitate to maintain the formula originally established by me as the true expression of the constitution of this compound.

The resumption of this inquiry has led me to some observations which afford an additional support of the composition of aniline-blue.

Rosaniline, when submitted to dry distillation, undergoes an irregular decomposition. Ammonia is evolved, a large amount of liquid bases (from 40 to 50 per cent.) passes over, and a porous mass of charcoal remains in the retort. The principal constituent of the liquid product is aniline.

Ethyl-rosaniline, the commercial aniline-violet, already manufactured on a large scale by Messrs. Simpson, Maule, and Nicholson, when distilled, exhibits similar phenomena. There is no difficulty in separating from the liquid product an appreciable amount of ethylaniline, the presence of which has been established by the examination of the platinum-salt.

The relation existing between aniline-violet, obtained by the action of iodide of ethyl, and aniline-red, cannot possibly be doubtful. Now, since analysis points out similar relations between aniline-blue and aniline-red, it became perfectly legitimate to anticipate, among the products of distillation of aniline-blue, i. e. of phenylated rosaniline, the presence of phenylated aniline, or diphenylamine, a substance which chemists had often, but vainly, endeavoured to prepare. Experiment has verified this anticipation.

Some weeks ago my friend, M. Charles Girard, Director of the Works of the Fuchsine Company at Lyons, had the kindness to transmit to me for examination some basic oils of high boiling-point which he had obtained by the destructive distillation of a considerable quantity of aniline-blue. The product of distillation which he forwarded to me was brown and viscid. When rectified, it furnished a slightly coloured liquid; at 300° the thermometer indicated the distillation of a definite compound.

The distillate which had passed between 280° and 300° solidified on addition of hydrochloric acid, a chloride difficultly soluble (more especially in concentrated hydrochloric acid) being formed. By washing with alcohol, and ultimately by crystallization from this liquid, the chloride was obtained in a state of purity. When treated with ammonia, it furnished colourless oily drops, which, after a few moments, solidified to a white crystalline

mass.

The crystals thus obtained possess a peculiar flower-like odour; their taste is aromatic, and afterwards burning. At 45° they fuse to a yellowish oil, distilling constantly, and without alteration, at 312° (corr.). They are almost insoluble in water, easily soluble in alcohol and ether. Neither in aqueous nor in alcoholic solution has the substance any alkaline reaction. When brought into contact with concentrated acids, the crystals are converted into the corresponding salts, which are remarkable for their instability. On the addition of water, the base separates in oily drops, rapidly solidifying to

crystals. The chloride, when washed with water, loses every trace of hydrochloric acid.

The analysis of the base has led to the formula.

[ocr errors][subsumed]

The composition of the chloride, which crystallizes from alcohol in concentrically grouped needles, assuming a bluish tint by contact with the air, is

12 H1, N, HCl.

C12

11

I do not believe that I am deceived in considering this compound as diphenylamine,

CH,

6

C12 H1, N=C, H, N.

12 11

6

H

It deserves, however, to be stated that the strict experimental demonstration of this mode of viewing the compound is still wanting, the ethylation of the substance presenting difficulties that I have not yet been able to overcome. I regret this gap, since the experience acquired in the study of xenylamine, isomeric with diphenylamine,

[merged small][subsumed][ocr errors][merged small][merged small][merged small]

and which for several weeks I regarded as the secondary phenyl-base, points out the necessity of consistently carrying out the process of ethylation in the examination of bases of this kind.

Diphenylamine exhibits a peculiar reaction, which, while it appears to reveal its relation to the colour-generating aniline, enables us to recognize In contact with concentrated nitric acid, the presence of the new base. diphenylamine, as well as its salts, assumes at once a magnificent blue coloration. The reaction succeeds best by pouring concentrated hydrochloric acid upon a crystal of the base, and then adding the nitric acid drop by drop. Immediately the whole liquid becomes intensely indigo-blue. Minute quantities of diphenylamine may in this manner be readily traced. I have thus been enabled to ascertain the presence of this body, or, at all events, of a substance exhibiting this particular reaction, in the products of distillation of rosaniline, leucaniline, and even of melaniline. The last experiment deserves particularly to be noticed, since it affords the general method for the production of the secondary aromatic monamines, which was hitherto wanting.

The substance possessing the blue colour is formed also by the action of other oxidizing agents. On adding chloride of platinum to a solution of the chloride, the liquid at once assumes a deep-blue colour. Only, from

very concentrated solutions, a platinum-salt is deposited exhibiting an undesirably blue tint.

When a mixture of diphenylamine and toluidine is submitted to one of the processes (treatment with chloride of mercury or arsenic acid) which, if phenylamine and toluidine had been employed, would have furnished rosaniline, a mass is formed which dissolves in alcohol with a magnificent blue coloration, and possesses the characters of a true colouring-matter.

An alcoholic solution of diphenylamine furnishes, on addition of bromine, a yellow crystalline precipitate, difficultly soluble in cold alcohol, but crystallizing from boiling alcohol in beautiful needles of a satiny lustre. According to analysis, they contain

[blocks in formation]

A mixture of diphenylamine and chloride of benzoyl, when heated, furnishes a thick oil, which solidifies on cooling. Washed with water and alkali, and recrystallized from boiling alcohol, in which it dissolves with difficulty, the new compound is obtained in beautiful white needles. Analysis has confirmed the theoretical anticipation,

[blocks in formation]

This substance has become the starting-point of some experiments which I shall here briefly mention, but to which I intend to return hereafter. On addition of ordinary concentrated nitric acid, the benzoyl-compound liquefies and dissolves. From this solution, water precipitates a lightyellow crystalline compound,

[blocks in formation]

which dissolves in alcoholic soda with a scarlet colour, splitting on ebullition into benzoic acid and reddish-yellow needles of nitro-diphenylamine,

[blocks in formation]

If, instead of ordinary nitric acid, a large excess of the strongest fuming nitric acid be employed, the solution deposits, on addition of water, a crys

Italline compound of a somewhat deeper yellow colour, containing probably

[blocks in formation]

This substance dissolves in alcoholic soda with a most magnificent crimson colour. Addition of water to the boiling liquid furnishes a yellow crystalline deposit, benzoate (?) of sodium remaining in solution.

The yellow powder is dinitro-diphenylamine. From boiling alcohol, it crystallizes in reddish needles, exhibiting a bluish metallic lustre. The analysis of the compound has led to the formula

[blocks in formation]

The chemical history of these compounds will be the subject of a special communication.

XVI. "A Table of the Mean Declination of the Magnet in each Decade from January 1858 to December 1863, derived from the Observations made at the Magnetic Observatory at Lisbon; showing the Annual Variation, or Semiannual Inequality to which that element is subject." Drawn up by the Superintendent of the Lisbon Observatory, Senhor DA SILVEIRA, and communicated by Major-General SABINE, R.A., President of the Royal Society. Received June 6, 1864.

I have much pleasure in communicating to the Fellows of the Royal Society a copy of a Table which I have received from the Superintendent of the Magnetic Observatory at Lisbon, containing the mean values of the Declination in each Decade from the commencement of 1858 to the close of 1863, with corrections applied for the mean secular change, and showing, in a final column, the difference in each decade of the observed from the mean annual value derived from the 216 decades. This Table is a counterpart of Table VII. in Art. XII. of the Philosophical Transactions for 1863, p. 292, differing only in the substitution in the Lisbon Table of decades for weeks, and the addition of the year 1863.

This general confirmation by the Lisbon Observatory of the annual variation to which the Declination is subject, "the north end of the magnet pointing more towards the East when the sun is north of the Equator, and more towards the West when the sun is south of the Equator," is very satisfactory. In the Lisbon Table the disturbances have not been eliminated.

Means of the West Declination at the Lisbon Observatory, from January 1858 to December 1863.

[blocks in formation]
« НазадПродовжити »