VIII. 0.1568 substance required 11.8 c.c. N/10 Na2CO3 for neutralisation.

Theory for a monobasic acid = 107 c.c. and 120 c.c. respectively. With caustic alkalis, the results are much higher, 0·1752 required 22 c.c. N/10 KOH.

Theory for a monobasic acid = 134 c.c.

Examination of Product C.-The air-dried crystals gave the following results.

0.1247

93

IX. 01395 gave 0·1317 CO2 and 0·0537 H2O. C = 25·74; H = 4·27. X. 0.1318 0.0501 C25.80; H = 4.29. The formula CHÃO,2H2O requires C = 26·08; H = 4·02 per cent. XI. Another specimen was heated at 80-85° in a current of hydrogen until the weight was constant.

0.2456 lost 0.0481. H2O: = 19.58.

Theory for a loss of 2H2O from C,H,O, = 19.56 per cent.

These results are identical with those obtained on analysis of the original acid. (For the sake of reference, we will call the original acid the a-modification, and the Product C the p-modification.)

The properties of the two are in many respects identical or very similar. Both give the characteristic violet coloration with ferric chloride and alkali, the behaviour on heating is much the same, and the solubilities appear to be almost identical, about 5 parts per 1000 at 15°. The accuracy of the solubility determinatious cannot, however, be depended on, owing to the unstable character of the aqueous solutions which decompose spontaneously even at low temperatures. The crystalline forms and the appearance are, however, altogether different, the a-acid crystallising in diamond-shaped plates, and the B-acid in prisms or needles. Both acids lose their water of crystallisation on heating, leaving white, amorphous powders, and, on dissolving these in small quantities of hot water, each crystallises out again in its original form, that is, the a-acid in diamond-shaped plates, and the B-acid in prisms.

The acid aniline salt of the B-acid appears to be much more stable than that of the a-acid, and the difference is very striking if the experiments are made side by side. Weighed quantities of the respective acids are dissolved in alcohol, and aniline is added in alcoholic solution in quantity calculated for the acid salt (1 mol. acid to 1 mol. aniline). The precipitates obtained are collected, washed with alcohol, and thoroughly drained with the aid of the pump; they are then ground up with small quantities of cold water, filtered, and the filtrate heated gradually to boiling under the same conditions. The salt of the a-acid, as previously shown, very soon begins to cloud, and eventually deposits a buff-yellow precipitate, whereas the salt of the p-acid remains perfectly clear for a considerable time. It is true that some

specimens of the aniline salt of the B-acid also showed a cloudiness after a time, but the difference from the a-salt, even then, is very easily seen. This slight clouding of the solution of the B-salt is probably due to the fact that it is very difficult to obtain specimens of B-acid entirely free from traces of the a-acid; examined under the microscope, one or two diamond-shaped crystals are sometimes found mixed with the prisms or needles. This circumstance may be due to the fact that the methods of purification are not perfect, or to a partial change back to the original form.

From the foregoing observations it seems evident that the difference between the a- and B-acids is more than a mere crystallographic one, and, considering the mode of formation of the B-acid, and the relative stability of its acid aniline salt, it appears not improbable that it represents the fumaroïd form, i.e., that it is dihydroxyfumaric acid. The formation of this acid from the corresponding maleinoïd form could be explained by the Van't Hoff- Wislicenus hypothesis in a manner similar to that which accounts for the transformation of maleïc into fumaric acid by the action of hydrogen bromide. The intermediate product might, for example, be tribromosuccinic acid or trihydroxysuccinic acid, which could lose hydrogen bromide or water, giving a fumaroïd derivative. Referring, however, to the two intermediate products which were isolated from the acetic acid hydrogen bromide reaction mentioned above, the following explanation may be suggested.

The Product B, having the formula C.H2O,, might be the anhydride, "internal ether," or lactonic acid, but, from its behaviour with sodium carbonate and with alkalis, and from the fact that its aqueous solution, on standing, readily yields the B-acid, there seems to be little doubt that it is the lactonic acid, having the fumaroïd constitution, COOH-C-O. This lactonic acid, it will be remembered, was proOH.C.CO

duced by heating the crystalline Product A, 2 mols. of acetic acid being given off at the same time. The acetic acid might be present as "acetic acid of crystallisation," but it seems more probable that the Product A is a compound formed by the addition of the elements of acetic anhydride to the original unsaturated dihydroxymaleïc acid, он

COOH-C-O.COCH,

COOH-C COCH,
он

* When the original acid is heated with amorphous phosphorus and bromine, a product is obtained which, on being dissolved in water, deposits crystals after a time, apparently identical with the B-acid, and a similar effect is slowly produced by aqueous hydrogen bromide.

This product might then, after "rotation," lose 2CH, COOH in the

This explanation is, of course, only offered as a suggestion. I hope shortly to make further observations on this B-acid, and also on the lactonic acid which appears to have some remarkable properties. The side-issues of the present work have, however, revealed so many interesting fields for investigation, that it is somewhat difficult to decide which should next be taken in hand.

University Laboratory, Cambridge,

March 17th, 1896.

ANNUAL GENERAL
GENERAL MEETING,

March 26, 1896.

Mr. VERNON HARCOURT, President, in the Chair.

THIRTY-ONE years ago I had the honour of being elected Secretary of the Chemical Society. We used then to meet on the ground-floor of the original Burlington House, which the artists now occupy, on the east side of the entrance, and it was during my eight years of office that the present home of the learned societies was built, and that we moved into the rooms in which we now meet. The collection of specimens presented to the Society, which it was thought in our early days would gradually furnish a chemical museum, was dispersed at the time of our removal, the decision having to be made whether we should appropriate a room and shelves to such a museum or not. Mr. John Williams put a modest price upon the articles, at which they were taken by various members of the Council. No doubt the decision was right. It requires an effort of the imagination to invest such specimens with a real individuality. Among my share was a small bottle of the beautiful, silky-red needles of chromic acid, now trioxide, prepared and presented by our founder, Mr. Warington. But the substance had become common, and one needed, in order to feel interest in the specimen, to rest upon the historical evidence that those were the actual crystals Mr. Warington had prepared. Another specimen I remember of native mercury from Idria. For many years it was religiously kept apart, but at last some laboratory boy, unconscious of the difference between it and other mercury, added it to the general stock. Many other specimens had succumbed to the property of slow chemical change, a property existing, no doubt, in a number of substances which, in our hurried way, we deal with before the year is out, and are not content to watch. It might by now have been of great interest to examine some of the decomposed specimens of this miscellaneous collection.

We decided against the museum, but arranged for a room adjoining our meeting room, which should be fitted up as a laboratory, and provided with such ordinary apparatus and materials as might help, and so encourage, authors to illustrate their communications experimentally. I fear this plan has failed, like that of a museum. Figures and formulæ, and drawings on the blackboard, form the chief part of what chemists now have to show to one another. But I observe that

the old love for an experiment, though it may have been most keen in the boyhood of our science, as in the boyhood of each one of us, still remains. When the liquefaction of air in a cooled test-tube is to be shown, or the phosphorescence of the platinocyanides under the penetrating influence of the Röntgen rays, we have even larger meetings than usual, and a still more interested audience. The feelings with which we first saw solid carbon dioxide, or evidence of the extension of the spectrum beyond the visible limits of red and violet, or the action of the screened off magnet, are re-awakened. In view of this fact, those who contribute to our proceedings should bear in mind that anything they may have to show will meet with a welcome sufficient to reward them for the trouble which the bringing and setting up of apparatus involves. It is not only such wonderful scientific discoveries as those to which I have referred, which should be illustrated here. We have been glad to see the simple production of acetylene, from some lumps of calcium carbide in a bottle, and some water in a dropping tube, the brilliant light which the gas gives, and the flame of its decomposition in a heated tube. We are also indebted to Professor Lewes for showing before us that cyanogen mixing with nitric oxide burns like a hydrocarbon. Further, novelty in apparatus is worth showing, even a new dephlegmator or nitrometer. In a few minutes, with a few words of description, every one can judge whether the apparatus shown is in any respects better than that which he is accustomed to use; and many a useful hint, or the germs of further improvements, may thus be imparted.

I have referred to experiments on acetylene, and this recalls the evenings we have spent in listening to a discussion of the nature of hydrocarbon flames, their temperature in different regions, and the causes of their luminosity. The attractive phenomenon of flame no longer holds the place it once held in chemical theory; but at long intervals, on two or three occasions, a discussion has arisen regarding what may be called the topography of flames. Indeed, the delimitation of the zones, and the estimation of the temperature and material constitution of portions of the flame, are so difficult that we cannot yet with confidence give a complete account of that which happens in any single flame. Before one of our recent discussions, I was asked by a friend to conclude the proceedings with a judicial summing up, and to declare which disputant was in the right. I declined to undertake the task. I do not underestimate the dignity, for which I am grateful to you, of occupying this chair; but it does not entitle, and certainly does not qualify, its holder to pronounce er cathedrâ on any subject as to which a difference of opinion exists between honest and capable investigators. Taking, however, the humbler position of a jury man I should have supported a verdict to this effect,