tions at 20°: a=+6·73, c=10·1488, 71, hence [a]n= +66·31°; a= +2·70°, c=4.0595, 7= 1, hence [a] = +66·51°. The silver salt is soluble in water, and does not decompose much on evaporating the solution. An estimation of silver in the salt gave the result 51.01 per cent., the calculated number being 51.43. The acid potassium and acid ammonium salts are crystalline. The normal sodium salt, in aqueous solution at 17°, showed the specific rotation +41·11° (c = 3·138); the residue left on evaporating the solution, dried at 120°, was found to contain 18.35 per cent. of sodium instead of the calculated number, 18:40. The calcium salt is very soluble, and was not obtained in the crystalline state. The barium salt, which is characteristic, is sparingly soluble in cold water, and crystallises readily in large, glassy prisms, containing apparently 4H,O, which is lost at 120-130°. Analysis of the anhydrous salt gave the following results. Found: C 27·78; H=3·77; Ba=39.94 and 40.12 per cent. An aqueous solution of the salt at 16° had the specific rotation +26 25° (c = 1·8092). Ethylic d-diethoxysuccinate is also obtained by the direct action of ethylic iodide and silver oxide on tartaric acid, but the yield is smaller than when the alkyl tartrate is used as the starting point. From 17 grams of tartaric acid we obtained in this way 12 grams of an ethereal oil having the same boiling point, and the same observed rotation, +85°, as the crude ethylic diethoxysuccinate prepared from ethylic tartrate. The optical effect of the replacement of the alcoholic hydrogen of tartaric acid by alkyl radicles is of the same nature as that which attends a similar substitution in lactic and malic acids; the sign of rotation, defined in the case of lactic acid as that of its salts, remains unchanged; a striking rise of activity, observable more particularly in the free acids and the ethereal salts, is produced, and the specific rotation of the acids in aqueous solutions of varying concentration becomes more constant. Thus, in passing from tartaric to diethoxysuccinic acid the molecular rotation of the ethylic salt is raised from +15·8° to +244·3°, and that of the free acid at similar concentration from +20-6° to +136 6°. The ionic rotation, however, does not experience a proportional rise, the result being that, whilst in the case of the three hydroxy-acids mentioned the molecular rotations of the alkali salts in dilute solution greatly exceed those of the free acids, these rotations become nearly equal in the case of the alkyloxypropionic compounds, and the order of their value is reversed in the case of the mono- and di-alkyloxysuccinic compounds, Our observations furnish a satisfactory explanation of the apparently anomalous results obtained by Rodger and Brame, which have been already referred to. An admixture of 6 per cent. of ethylic d-di ethoxysuccinate would suffice to account for the high rotation of the ethylic tartrate which they prepared by the silver salt method, but the difference between the rotations of the products of hydrolysis of such a mixture and of pure ethylic tartrate respectively would not, under the conditions of the experiment described by them, amount to more than 0.1-0.2°.* The action of alkyl iodides and silver oxide on the alkyl salts of optically active hydroxy-acids furnishes a general method of obtaining the active alkyloxy-acids. We have used the method with success for the preparation of alkyloxypropionic and alkyloxyphenylacetic acids from active lactic and mandelic acids, and we are at present studying the application of the alkylating agent to the alkyl tartrates in general and to other compounds. UNITED COLLEGE OF ST. SALVATOR AND ST. LEONARD, XIX.-Determination of the Constitution of Fatty Acids. Part I. By ARTHUR WILLIAM CROSSLEY and HENRY RONDEL LE SUeur. SOME short time ago one of us, in conjunction with Professor Perkin (Trans., 1898, 73, 1), described an investigation of a complicated mixture of fatty acids derived from the fusion of camphoric acid with alkalis; as the difficulties encountered in identifying some of the fatty acids were very great, it was considered desirable to try and devise a method for the determination of the constitution of such acids, and the object of this paper is to give a short account of experiments which have been carried out in this direction. So far as our present experiments go, we think they may be described as satisfactory, and although the method may not be an infallible one, it seems likely to prove of considerable importance as a means of establishing the constitution of organic acids. 2 The method of procedure which was suggested to us by Professor Perkin is the following. Starting with a fatty acid, X·CH2· CH2· COOH, this is first converted into the ethylic salt of the monobromo-derivative by Volhard's process (Annalen, 1887, 242, 61); from the work of * The experiment referred to was made on the methylic tartrates, but this would not materially alter the result as stated above. Auwers and Bernhardi (Ber., 1891, 24, 2209) and others, there can be no doubt that, under these conditions, the bromine atom takes up the a-position, yielding the substance X CH, CHBr COOEt. The. brom-ethereal salt is then treated with quinoline or diethylaniline (compare Weinig, Annalen, 1894, 280, 253), whereby the elements of hydrobromic acid are removed, and the ethylic salt of an unsaturated acid of the acrylic series, X∙CH:CH·COOEt, is produced. The free acid obtained from this salt by hydrolysis is then oxidised, first with potassium permanganate, giving rise to the corresponding dihydroxy-acid, X∙CH(OH)·CH(OH).COOH, and then with chromic acid, when the molecule is broken down at the position occupied by the double bond in the unsaturated acid, giving X-COOH and COOH COOH. The result is, therefore, the production of oxalic acid and a fatty acid (or ketone) containing two carbon atoms less than the original acid, and as the number of isomerides decreases greatly with loss of two carbon atoms, the possibility of identification is much enhanced. We have carried out this process with three acids, namely, valeric, iso-valeric, and iso-butylacetic acids, as we considered that the oxidation products of the acids of the acrylic series corresponding with these fatty acids would be typical examples of what might be expected to be met with in actual determinations. Thus valeric acid gives ethylacrylic acid, and this, on oxidation, propionic acid (normal acid); iso-valeric acid gives dimethylacrylic acid, which then yields acetone (ketone); and iso-butylacetic acid gives iso-propylacrylic acid, and, on oxidation, iso-butyric acid (iso-acid). With the three acids mentioned, the method works well. In all cases we have been careful to note the yields of substances obtained in the various stages, and there is here appended a tabulated list of results. The numbers express the percentage yields, and are referred, in the case of the unsaturated ethereal salt and acid, to the amounts theoretically obtainable from the brom-ethereal salt employed; and in the case of the "acid or ketone produced on oxidation," to the amounts theoretically obtainable from the unsaturated acid used. The poor yield of unsaturated ethereal salt obtained from ethylic bromovalerate is accounted for by the fact that there is also pro duced a considerable quantity of some substance of higher boiling point, which is at present under investigation; and the comparatively small amount of the solid dimethylacrylic acid obtained from its ethylic salt is due to the fact that an oily substance is produced at the same time (see page 164). In no case was oxalic acid identified in the products of the reaction, nor could it be expected to resist the action of the strong oxidising agents employed. We have experimented with both quinoline and diethylaniline, using them as reagents for the elimination of the elements of hydrobromic acid, and find that, with the lower fatty acids, the one gives quite as good results as the other, but with the higher fatty acids. diethylaniline is to be preferred. For example, in the case of ethylic bromisobutylacetate, the 42 per cent. yield of ethylic isopropyl acrylate, obtained when using quinoline, was increased to 70 per cent. by employing diethylaniline. Quinoline always gives rise to tarry products, which are not easy or agreeable to work with, whereas diethylaniline does not; in the latter case, however, the substances require to be heated together for a much longer time, and it is very difficult to eliminate the last traces of hydrobromic acid. As, however, the unsaturated ethereal salts are subsequently heated with alcoholic potash, the latter objection is of no great moment. We intend to further test the efficacy of the method by trying it on other acids, such as (a) stearic acid, and from preliminary experiments already made with this acid, it seems highly probable that the various reactions will take place as expected. The insolubility of the hydroxylated higher fatty acids in water may render the oxidation with chromic acid a difficult operation, in which case it will be of interest to see whether fusion with potash will serve a similar purpose. (b) It will be noticed that, among the acids examined, none contain alkyl groups in the a-position. In such a case, as, for example, ethylisopropylacrylic acid, quite a new point is raised. This acid, C2H CH(CH)·COOH, still contains one a-hydrogen atom, and should, therefore, yield an a-brom-ethereal salt in the usual manner; but when the latter is treated with quinoline, there are two possible ways in which hydrobromic acid may be eliminated (compare Perkin, Trans., 1896, 69, 1466), giving rise to The study of the oxidation products of the unsaturated acid or acids produced would, therefore, be of special importance. (c) The method may also prove to be applicable in the case of dibasic acids, and we propose to try it on pimelic (isopropylsuccinic) acid. EXPERIMENTAL. Acetone from Isovaleric Acid. Instead of starting with isovaleric acid, the ethylic salt of a-bromisovalerate supplied by Kahlbaum was employed, which, on distillation, boiled constantly at 185-186°, and a bromine determination gave the following numbers. 0.2514 gave 0.2275 AgBr. Br=38.50. CH,Br COOCH, requires Br=38.28 per cent. Treatment of Ethylic a-Bromisovalerate with Quinoline.-Weinig (Annalen, 1894, 280, 253) has shown that diethylaniline may be used instead of alcoholic potash for the elimination of the elements of hydrobromic acid, and later Perkin and Goodwin (this Journal, 1896, 69, 1470) described experiments in which they employed quinoline for the preparation of dimethylacrylic acid from ethylic a-bromisovalerate. We have followed their instructions exactly, using 50 grams (1 mol.) of the brom-ethereal salt and 70 grams (2 mols.) of freshly distilled coal-tar quinoline; on fractionating the product, it was found to distil between 153° and 155° as a colourless oil of penetrating odour. The yield is 80 per cent. of the theoretical. This ethereal salt is readily saponified by alcoholic potash, and the dimethylacrylic acid formed boils constantly at a temperature of 114° under a pressure of 40 mm. On standing, the distillate solidifies almost completely to a mass of needle-shaped crystals, which, after being freed from the mother liquor by spreading on a porous plate and recrystallisation from light petroleum (b. p. 60-80°), melted at 68-5-69°, and gave the following results on analysis. 0.1047 gave 0.2296 CO2 and 0·0744 H2O. C-59·80; H=7·90. CHO2 requires C=60·00; H=8.00 per cent. The yield of pure acid is from 55-60 per cent. of the theoretical obtainable from the brom-ethereal salt employed. On extracting the porous plate just mentioned with ether, a small amount of an oily liquid was obtained which showed no signs of solidifying even after long standing, and which was not further investigated. Perkin and Goodwin (loc. cit.) also mention this oily bye-product. Treatment of Ethylic a-Bromisovalerate with Diethylaniline.—In using quinoline for the elimination of the elements of hydrobromic acid, there is always a considerable quantity of tarry matter formed, and in later experiments we found that diethylaniline could be used with |