I have already described to the Society several mineral species new to science as occurring in Cornwall. During my experiments I have obtained numerous results relating to species already described, some of which, however, have not hitherto been recognized as Cornish, or are of rare occurrence.

Melaconite. This mineral was described by me in March last as occurring in a definite crystallized form. I had then observed forms quite incompatible with the cubical system, and had communicated the fact to Professor Miller of Cambridge: in my notice in the Chemical News I stated that it was my intention to measure the crystals, but Professor Maskelyne soon after read a paper on the crystalline form of the mineral before the British Association last summer, and exhausted the subject, although the paper has not yet been published in full. I cannot regret that the crystallographic work has fallen into hands so much more competent to deal with it than my own.

Marmatite. This black variety of blende occurs in Cornwall. The composition is similar to the Marmato specimen analysed by Boussingault, and is represented by the expression 4ZnS.FeS.

Erinite and Cornwallite.-The only reported locality of erinite is Limerick. But I have a few grains, which I have identified with this species, from Cornwall. I have met more frequently with Cornwallite, a perfectly distinct species. But there exists an impure chrysocolla containing phosphate which has occasionally been mistaken for the latter species.

Autunite.-I have examined a Cornish specimen of autunite incrusting chalcolite, and found it as free from copper as the St. Symphorien specimens.

XIV.-Action of Nitrous Acid on Naphthylamine.

By ERNEST T. CHAPMAN.

In their first paper on this subject,* Messrs. Perkin and Church state that by the action of nitrous acid on naphthylamine, or rather by the action of a soluble nitrite on a salt of naphthylamine, a red base was obtained, having the peculiar property of turning violet on

* Quarterly Journal of Chemical Society, vol. ix, page 1, et seq.

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the addition of acids, named by them azo-dinaphthyldiamine. They state that this substance is analogous to, or identical with, one obtained from dinitronaphthalene by the action of nascent hydrogen; and from an analysis of the former substance they were led to the formula C,H,N2O. Were this formula correct, the production of the compound in question by the action of nascent hydrogen on dinitronaphthalene would be intelligible; but as they subsequently succeeded in obtaining this compound in a state of purity, and as it was then found to possess the composition C20H15N3*, it is by no means clear how such a compound could be formed in the manner above stated. And in fact I could not obtain any evidence of the substance by this method, but, on the contrary, obtained a compound of a dark green colour possessing feeble basic properties; it dissolves in alcohol, forming a tolerably bright green solution. Alcohol acidified with hydrochloric acid dissolves much more of it, but with a dirty olive-green colour. Ammonia precipitates it from this solution with its original colour. I could not make the compound crystallise, and have not further examined it.

Messrs. Perkin and Church prepare azo-dinaphthyldiamine by acting on 2 eq. of naphthylamine with 1 eq. of nitrous acid, and effect this object by acting on 2 eq. of hydrochlorate of naphthylamine with 1 eq. of nitrite of potash and 1 eq. of potash†— 2(C10H,N.HCI) + KNO2 + KHO = C20H15N3+2KCl + 3H2O.

The process answers admirably; the only points needing attention are that the solution of hydrochlorate of naphthylamine must be cold and dilute.†

The liquid is at once filled with a white precipitate, which rapidly turns scarlet, and gradually deposits. This is the substance in question; it has only to be filtered off, washed with cold water, and crystallised from alcohol; it is then in a state of perfect purity.

I discovered this substance amongst the products of the action

*Chem. Soc. J. [2] i, 207.

+ Azo-dinaphthyldiamine is not obtained by acting upon a mixture of 1 eq. of naphthylamine and 1 eq. of hydrochlorate of naphthylamine dissolved in alcohol with 1 eq. of nitrite of potassium. If such a mixture be made, the liquid yields no crystals on evaporation, but a pitch-like substance gradually separates, which dissolves in alcohol with violet colour, turning red on addition of acids. The substance, when quite cold, shows faint signs of crystallisation.

This fact was kindly communicated to me by Prof. Church.

of zinc-ethyl on a mixture of nitro- and dinitro-naphthalene. The observation was accidentally made. I supposed myself to be acting on pure dinitronaphthalene; but on repeating the experiment I could not obtain the same result. As the dinitronaphthalene employed in the first case had only been washed in boiling alcohol and not recrystallised, I supposed that it might contain a small proportion of nitronaphthalene, and that this substance might produce the base in question. As I knew from previous experiments that it was incapable of doing so alone, I concluded that a mixture of the two was necessary to produce the base, and found this conclusion to be borne out by experiment. At the time of making this observation, I was unaquainted with Messrs. Perkin and Church's second paper, and therefore supposed that I had a new substance in hand. Nascent hydrogen, at least in the form of H2S, will reduce dinitronaphthalene to ninaphthylamine, C,,H,N2O, and the same agent will reduce nitronaphthalene to naphthylamine C1,H,N. Now if these two substances were to unite, and water were eliminated, C20H15N3 (azo-dinaphthyldiamine), would be produced: C1,H,N2O + C10H,N=C20H15N3 + H2O. And, in fact, on treating a mixture of dinitronaphthalene and nitronaphthalene in alcoholic solution with zinc and hydrochloric acid, the splendid violet colour of azo-dinaphthyldiamine is produced. The colour of course very soon goes, and is not produced for some time after the mixture is made. I intend to examine this reaction more fully.

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If, instead of employing in the preparation of azo-dinaphthyldiamine, 1 eq. of nitrous acid to 2 eq. of naphthylamine, we take 1 eq. of each, we still obtain the substance, but in an impure state; and if some of this impure substance be dissolved in alcohol, hydrochloric acid added, and then ether, and the whole diluted with water, the ether will rise to the surface coloured coppery-red, the other portion of the liquid being violet. On separating and evaporating off the ether, a brownish gummy residue remains. On liberating the azo-dinaphthyldiamine by means of ammonia, it will be found that it now readily crystallises from alcohol, which it would not do before this purification. As the gummy substance dissolved by this ether seemed to be formed only when nitrous acid was present in excess, I proceeded to try if I could obtain it by mixing an acidified solution of hydrochlorate of naphthylamine with a solution of nitrite also acidulated; under these circumstances the liquids remained clear, but a slight effervescence took place, the gas liberated being apparently nitrogen; in the course of about ten

minutes the liquid began to get a little thick, and a pitch-like substance gradually separated, gas being evolved during the whole process. If during the earlier stages of this process, the liquid be filtered off and ammonia added, or if before the black substance begins to separate, ammonia be added, azo-dinaphthyldiamine will be precipitated apparently in a state of great purity; at least it crystallises very easily. If instead of employing ammonia, we employ an alcoholic solution of naphthylamine, adding it drop by drop, so long as the white spot formed at first by its addition disappears, we shall arrive at a point at which the addition of a drop of the naphthylamine solution will cause azo-dinaphthyldiamine to separate from the fluid.

Potash and soda produce a reddish-brown precipitate, altogether devoid of basic properties. This substance, if filtered off, washed first with very dilute hydrochloric acid, then with water, and dried at 100° C. forms a chocolate-coloured powder. It is odourless and tasteless, altogether insoluble in water, hot or cold, very slightly soluble in alcohol, slightly more so in ether, but very readily in bisulphide of carbon; benzole also dissolves it pretty freely, but it would not crystallise from any of these liquids. It dissolves in concentrated sulphuric acid with a green colour, but regains its original colour on dilution, and is precipitated apparently unaltered. Concentrated nitric acid also dissolves it, but at the same time alters its composition. The colour of its alcoholic solution is not in the slightest degree affected by acids, and it forms no compounds, so far as I am aware, with acids or bases, or in fact with any class of substances whatsoever. Acted upon by nascent hydrogen it was rapidly decolorised. Heated on the platinumknife, it melts, gives off a little red fume, and leaves a very difficultly combustible carbonaceous residue; it was analysed by burning it in a stream of common air.

Two nitrogen determinations by Dumas' method gave the following results :

From these numbers, excluding the hydrogen in the first analysis, I obtained the following average percentages :—

C. 82.1

H. 4.87

N. 7.93

O. (by diff.) 5.10

but could not obtain a satisfactory formula.

Of course as there is sufficient hydrochloric acid present to saturate both the naphthylamine and the potash of the nitrite, the reaction really takes place on hydrochlorate of naphthylamine, and not on naphthylamine itself. It is possible, therefore, that the nitrous acid effects changes in the naphthylamine-salt, without completely breaking it up, and that it is the addition of the alkali which completes the reaction.

The liquid filtered off after the deposit of the brown substance contained no organic matter.

The black substance before-mentioned as being formed when a solution of hydrochlorate of naphthylamine is allowed to stand with an excess of nitrite of potassium and hydrochloric acid, is, like the brown substance, uncrystallisable, and soluble only with great difficulty in alcohol, ether, or bisulphide of carbon. It forms a yellow solution. It is soluble to a considerable extent in alcoholic ammonia. This solution is brown, and the substance is precipitated from it, apparently unchanged, by the addition of acids. It will not bear a temperature of 100° without undergoing partial decomposition. If heated to a 100° for a considerable time, it partially melts and gives off gas; after this it becomes hard again and is found to have lost about 6 per cent. of its weight. I could obtain no compound with it whatsoever. Its solution is easily decolorised by nascent hydrogen. Sulphurous acid has no effect upon it. Chlorine also seems to be without action, at least in the cold. Sulphuric acid dissolves it without evolution of gas, but it is not re-precipitated in an unchanged form on dilution. Concentrated nitric acid also dissolves it without evolution of gas. It cannot be formed by the action of nitrous