One of these exceptions is that afforded by the formation from naphthalene 1: 3′ disulphonic acid on nitration of a nitro-acid of the formula

S

NO,

(cf. Chem. Soc. Proceedings,' 1891, p. 27); this acid, however, is but a subsidiary product, the main product being an acid of the formula

NO, S

S

It has long been known that when the 1: 4' disulphonic acid is nitrated, it yields an a-nitro-acid; recently Mr. Wynne and the writer have found that the product also contains the isomeric B-nitro-acid.

Other exceptions are afforded by the production of beta-chloro- and bromo-naphthalene on chlorination and bromination of naphthalene;1 and by the presence of a certain proportion of beta-naphthylamine in commercial alpha-naphthylamine-a proof that naphthalene yields some betanitronaphthalene on nitration; the writer's attention has been called to this last fact both by Dr. H. Caro and by Professor Noelting.

Lastly Mr. Rossiter and the writer have found that beta-naphthol when brominated yields a dibromo-derivative of the formula

and in this case there appears to be no alpha-compound formed, so that the departure from the alpha-law is complete.

But the explanation of these results is not difficult. In no case probably is the substitution derivative the direct product of change; but its formation is preceded by that of an addition compound. This is generally admitted in the case of chloro- and bromo-derivatives, but evidence of the formation of addition compounds has not hitherto been forthcoming in other cases. Mr. Rossiter and the writer, however, have recently given proof that a compound with nitric acid is initially formed in the process of nitration.2 Obviously, in the case of a symmetrical molecule such as that of bromine, either an alpha- or a beta-derivative will result, according as either the beta- or the alpha-atom of bromine becomes eliminated from the bromide, thus:

HBr

HBr

=

The alpha-law in this case is expressed by saying that in the main the tendency is for the beta-bromine atom to be removed.

In the case of a dissymmetrical molecule, such as that of nitric acid, the formation of the one or the other derivative will depend on the nature of the addition compound-i.e., on the distribution of the radicles of the acid-assuming them to be distributed' when addition takes place, thus:

:

In this case the alpha-law is expressed in the statement that in the main the tendency is for the acid radicle to assume an alpha-position in the addition compound first formed.

This question has already been discussed by Mr. Wynne and the writer with reference to the tetra-chlorides of naphthalene and of its derivatives, naphthalene tetrachloride affording the three possible dichloronaphthalenes, but the 1:3 compound in largest and the 1:2 in least proportion, thus:

The behaviour of the substituted chlorides is as follows:

Cl

The influence of the substituent both as affecting the addition of chlorine and the elimination of hydrogen chloride is especially noteworthy. It will be seen that the sulphochlorides behave alike, but the two chloronaphthalenes dissimilarly towards chlorine, and that each compound decomposes in a manner peculiar to itself on treatment with alcoholic potash.

As yet no evidence has been obtained that a beta-bromo-, chloro-, or nitro-derivative may result by isomeric change from a previously formed alpha-derivative.

With regard to the sulphonic acids, on reference to the previous table in which the constitution of the acids formed on sulphonating the ten dichloronaphthalenes is indicated, it will be observed that in some cases an a- and in some cases a B-sulphonic acid is formed, or a mixture of both. Mr. Wynne and the writer have expressed the opinion that the a-acid is always initially produced, and that in some cases this is so unstable that it spontaneously passes over into the B-isomeride and escapes observation, while in others it is partially preserved. They base this conclusion on the fact that in all cases hitherto studied in which both acids are formed it is possible to convert the a- into the B-acid by heating. Thus 1: 2-dichloronaphthalene affords about two-thirds a- and one-third B-acid; but when the product is heated the latter is practically the sole product. In like manner the initial product of sulphonation from 1: 3-dichloronaphthalene contains about one-fifth B-acid; but if it be heated at 160° during eighteen hours complete conversion into the ẞ-iso-· meride is effected.

Should this conclusion with reference to the manner in which betasulphonic acids are formed be ultimately established it would follow that, unlike nitric acid, sulphonating agents regularly act in one way, and that the formation of the addition compound takes place in such a manner that the sulphonic radicle always attaches itself in an alpha-position.

Isomeric change in the case of sulphonic acids. The problems which this subject presents are of extreme interest; some idea of their character is afforded by the following example. When heated at about 150-160° 1: 4 a-chloronaphthalene sulphonic acid undergoes a change into the more symmetrical alpha-isomeride, while 2: 1'-ẞ-chloronaphthalenesulphonic acid is converted in a similar manner into the more symmetrical betaisomeride-results which may be regarded as indicative of a tendency to a final state of symmetry, thus :

In the case of the dichlorosulphonic acids it is noteworthy that the

position ultimately taken up by the SOH radicle appears to be determined by the beta-chlorine-atom, perhaps because the B-sulphonic acids are the most degraded' products, thus:

With reference to these examples it may be pointed out that the apparent passage of the sulphonic radicle in the one case from one nucleus into the other, in another from an alpha- into the contiguous beta-, and in a third from an alpha- into the more distant beta-position, are remarkable variations of the phenomenon of intramolecular mobility.

There is a striking difference in the behaviour of the 1 : 4, 1: 4', and 1: 2 aa-dichloronaphthalenes, to which attention may be directed, the nonformation of the acid containing a chlorine atom and the sulphonic radicle in the 11' position being noteworthy, thus:

In the case of the 1: 4 and 1 : 4' compounds the sulphonic radicle is obviously influenced in two directions, and may be said to take up a mean position.

A case of isomeric change which at present appears altogether paradoxical is that which is said to occur on heating sodium naphthionate (NH, SO,Na=1:4) at 200-250°, whereby it is converted into the isomeric 12-compound.

:

The foregoing brief reference to the work of the Committee will suffice to show that the study of naphthalene derivatives is fraught with interest, more especially as it is to be anticipated that results of general application will be obtained in the course of the inquiry..

Fifth Report of the Committee, consisting of Professors TILDEN, MCLEOD, PICKERING, RAMSAY, and YOUNG and Drs. A. R. LEEDS and NICOL (Secretary), appointed for the purpose of reporting on the Bibliography of Solution.

DURING the past year no progress has been made with the work of cataloguing the papers on Solution in the few remaining selected journals.

The Committee invite the co-operation of members who have access to large scientific libraries and are willing to take an active part in the work.

Fifth Report of the Committee, consisting of Professors TILDEN and RAMSAY and Dr. NICOL (Secretary), appointed for the purpose of investigating the Properties of Solutions.

THE Committee have to report that, owing to the pressure of other work, but little progress has been made with experiments on the atomic volumes of carbon, hydrogen, and oxygen when substances containing these elements are dissolved in water or other solvents. A preliminary research on the volume of oxygen in the oxy-acids of chlorine, bromine, and iodine has been completed with somewhat startling results, which lead the Committee to hope that valuable data will be obtained when the work is complete.

Third Report of the Committee, consisting of Professor ROBERTSAUSTEN (Chairman), Sir F. ABEL, Messrs. E. RILEY and J. SPILLER, Professor J. W. LANGLEY, Mr. G. J. SNELUS, Professor TILDEN, and Mr. THOMAS TURNER (Secretary), appointed to consider the best method of establishing an International Standard for the Analysis of Iron and Steel. (Drawn up by the Secretary.)

IN the two previous reports of this Committee the objects of the Committee were defined, and an account was given of the preparation and distribution by the American Committee of four out of the five international steel standards which Professor Langley had been requested and had kindly undertaken to prepare. A year ago it was hoped that a final report would be presented at the Cardiff meeting, but, unfortunately, this hope has not been realised, and the completion of the work has been deferred. In the second report mention was made of the fact that the American Committee had entered upon an investigation of the relative accuracy of different methods of analysis, particularly in connection with the estimation of carbon in steel. This work was not considered within the province of the British Association Committee when its objects were 1891.

T