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Isoquinoline is conveniently prepared by heating dichlorisoquinoline (3 grams), and hydriodic acid, sp. gr. 1.96 (18 c.c.) for five hours at 230°. The product is treated with alkali, and steam distilled; the distillate being treated with hydrochloric acid and again steam distilled to remove the unchanged chloro-base. Isoquinoline melts at 20-22°, and boils at 236-236-5°. The ethiodide crystallises in goldcoloured plates melting at 147-148°, readily soluble in water and in warm alcohol. N. H. M.

Synthesis of Hydroxyquinolinecarboxylic Acid. By E. LIPPMANN and F. FLEISSNER (Ber., 19, 2467-2471).-Unlike ordinary phenol-derivatives, the potassium compound of orthohydroxyquinoline is not acted on by carbonic anhydride even at 300°. When, however, nascent carbonic anhydride (obtained by the action of potash on carbon tetrachloride) is employed, action takes place. Orthohydroxyquinoline, carbon tetrachloride, and caustic potash are mixed in alcoholic solution in the proportions necessary for the equation C,NH,0 + CC + 6KHO = 4KČI + C‚NH¿(OK)·COOK + 4H2O, and the whole boiled for 12 hours. The product contains hydroxyquinolinecarboxylic acid, OH C,NH, COOH, which when purified crystallises in yellow prisms melting at 280°. This acid agrees in its salts and in all its properties, save melting point and oxidation products, with the a-hydroxycinchonic acid (m. p. 254-256°) obtained by Weidel and Cobenzl from sulphocinchonic acid (Abstr., 1881, 742). The acid is sparingly soluble in the ordinary solvents. It dissolves in dilute hydrochloric acid to form a hydrochloride, which is precipitated on the addition of concentrated hydrochloric acid in the form of glistening needles. The platinochloride forms unstable, bright yellow needles. The acid forms a normal barium salt, the pale yellow solution of which, on the addition of baryta-water, yields white needles of the basic barium salt C1NH,BaO3 + H2O; these only part with their water of crystallisation at 140-150°. The silver salt is precipitated in the form of pale lemon-yellow flocks, which soon change to microscopic needles. The aqueous solution of the acid gives a green coloration with ferric chloride, but none with ferrous sulphate. When subjected to dry distillation, the acid yields orthohydroxyquinoline.

When oxidised by potassium permanganate in alkaline solution, the acid yields a pyridinedicarboxylic acid, C,NH,O, forming bright yellow crystals melting at 234-235°. With ferrous sulphate, it gives a blood-red coloration, and forms a silver salt which is gelatinous when first precipitated, but soon becomes crystalline. This acid is probably identical with Böttinger's pyridinedicarboxylic acid, and isomeric with Weidel's isocinchomeronic acid.

Weidel and Cobenzl's a-hydroxycinchonic acid, when similarly oxidised, yields a-pyridinetricarboxylic acid. The authors are further investigating this subject. L. T. T.

Peculiar Formation of B-Diquinoline. By O. FISCHER and H. VAN LOO (Ber., 19, 2471-2476).-This is a continuation of the authors' previous work (Abstr., 1884, 1372). When B-diquinoline is heated with ethyl iodide in closed tubes at 90-100°, B-diquinoline

ethiodide, CN2H12EtI, is formed in long, ruby-red crystals. It is very unstable, and is decomposed by water and by boiling alcohol. No diethiodide could be obtained. When bromine is allowed to act on B-diquinoline in chloroform solution, a tetrabromo-additive product, CIN HBr, is produced. This crystallises in pale yellow needles melting at 1920, and is decomposed at once by sulphurous acid, diquinoline sulphate being formed. B-Diquinolinedisulphonic acid, CIN2H10 (SO3H)2, is produced when B-diquinoline is heated with a large excess of fuming sulphuric acid. It is very soluble in water, and is precipitated from this solution by a mixture of alcohol and ether in yellowish flocks. Its potassium salt crystallises from 50 per cent. alcohol in glistening white prisms containing 3 mols. H2O. The anaquinolinecarboxylic acid described in the former paper (loc. cit.), as obtained by the oxidation of the base by chromic acid in acetic solution, is undoubtedly identical with that lately obtained by Skraup and Brunner (m. p. 247°). The melting point previously given by the authors was obtained from a sample crystallised from benzene; when crystallised from water, it melts at 248-249°. The author considers this acid to be metaquinolinecarboxylic acid, and that the name anaquinolinecarboxylic acid should be transferred to the acid melting at 357°, and hitherto designated metaquinolinecarboxylic acid. If chromic acid is dissolved in sulphuric acid in place of acetic acid, the oxidation takes place in quite a different way. Under these circumstances pyridylquinolinecarboxylic acid, C,NH C2NH, COOH, is formed. This crystallises in glistening needles, which melt with decomposition at 271-273°. It is sparingly soluble in water, easily in alcohol, and forms salts both with acids and bases. The silver salt, when heated, yields a pyridylquinoline, C1N2H10, which crystallises in white needles melting at 104°, and gives a reddish-yellow crystalline platinochloride. L. T. T.

Piperidine Bases. By A. LADENBURG (Compt. rend., 103, 747— 749). The bases are obtained by treating boiling alcoholic solutions of the corresponding pyridine bases with a large excess of sodium.

Piperidine obtained in this way is identical with the base prepared from piperine. a-Methylpiperidine or a-pipecoline boils at 118-119°, has the same odour as piperidine, and dissolves readily in water; sp. gr. at 0° = 0.860. The hydrochloride is very soluble, but not deliquescent, and melts at 189°. The hydrobromide is less soluble, and forms confused needles which melt at 182°; the platinochloride is very soluble. With carbon bisulphide, the base yields a thiocarbamate, CS2, 2CH3N, which crystallises readily, melts at 118°, and is analogous to that formed from piperidine. B-Methylpiperidine or B-pipecoline boils at 125°, and dissolves readily in water; sp. gr. at 0° 0·8684. The hydriodide crystallises in beautiful, non-deliquescent needles, which melt at 131°. It combines with cadmium iodide, forming the compound CdI2,2C6H3NHI, a white precipitate soluble in warm water, from which it crystallises in white tables melting at 145°. The platinochloride is somewhat soluble, and forms orange prisms melting at 192°; the aurochloride is very soluble, and melts at 131°; the picrate melts at 136°, ax-Dimethylpiperidine or aa'-lupetidine boils at 128

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130°, and is very soluble in water and alcohol; sp. gr. at 0° = 0.8492. The hydrochloride and hydrobromide crystallise in non-deliquescent needles; the platinochloride forms large orange crystals which melt at 212°. ay-Dimethypiperidine boils at 141°, has an odour of piperidine, and dissolves readily in water, though not in all proportions; sp. gr. at 0° 08615. The hydrochloride crystallises in beautiful needles which melt at 235°; the hydrobromide is even more soluble; the platinochloride is not very soluble, and crystallises in nodules; the aurochloride is an oil. a-Ethylpiperidine boils at 143°, and dissolves slightly in water, but separates from the solution on heating, and has an odour resembling that of piperidine and conicine; sp. gr. at 0° 0-8674. The hydrochloride forms non-deliquescent crystals; the platinochloride crystallises in large tables which melt at 178°. The methyl-derivative boils at 149-152°; sp. gr. at 0° = 0·8495. -Ethylpiperidine boils at 157°, has a disagreeable odour, is only slightly soluble in cold water, and still less soluble in warm water; sp. gr. at 0° 0-8795. The hydrochloride is deliquescent; the platinochloride forms yellow tables which melt at 170-173°; the aurochloride crystallises from warm water in lamelle which melt at 105°. a-Isopropylpiperidine boils at 160-162°, and is slightly soluble in water, but separates from the solution when gently heated; sp. gr. at 0° = 0.8676. Its odour and its properties generally resemble those of its isomeride, conicine, but it is much less poisonous. The platinochloride is much less soluble in water, and is not soluble in alcohol or ether; it melts at 193°; the hydrochloride melts at 240°, the hydrobromide at 230°, the hydriodide at 2420. All these derivatives crystallise readily. The iodide combines with cadmium iodide, forming a slightly soluble double salt, which crystallises readily and melts at 132°. The picrate and aurochloride crystallise readily, and are only slightly soluble. With carbon bisulphide, the base yields a crystalline compound, CS(CHN)SH,C,H,N, which melts at 105°, dissolves readily in alcohol, but is only slightly soluble in water. The methyl-derivative of a-isopropylpiperidine boils at 166°; sp. gr. at 0° 08593. hydrochloride is extremely soluble in water; the aurochloride forms shining lamellæ, and is also very soluble in water; the platinochloride is somewhat soluble, and melts at 100°; the picrate crystallises readily, and melts at 149°. -Isopropylpiperidine boils at 168-171°, dissolves slightly in water, and has a very disagreeable odour. The hydrochloride crystallises, but is not stable in moist air; the platinochloride is crystalline, and is only slightly soluble in water, but dissolves in alcohol and ether, and melts at 172°; the aurochloride is also crystalline, and only slightly soluble. C. H. B.

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Method of Preparing Extracts of Pepsin. By W. PODWYSSOZKI (Pflüger's Archiv, 39, 62-74).-If the gastric mucous membrane of carnivora and herbivora be placed in glycerol almost immediately after death, very little pepsin is extracted.

Ebstein and Grützner state that glycerol dissolves pepsin only, but the author finds that a certain amount of pepsin precursor, or as he terms it "propepsin," is dissolved also.

Mucous membrane exhausted with glycerol still yields an important

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amount of pepsin when treated with hydrochloric acid or hydrochloric acid and glycerol. It appears, therefore, that gastric mucous membrane contains two propepsins, one soluble in glycerol, the other insoluble.

If the mucous membrane is kept in a warm place for 24 hours before it is extracted, a much larger yield of pepsin is obtained, provided no putrefaction has set in.

Hydrogen and carbonic anhydride have no influence on the formation of pepsin, but oxygen, on the other hand, appears to favour its development; more pepsin is formed when the mucous membrane is allowed to remain in contact with oxygen than when it is in contact with air.

Chlorine gas passed through any extract entirely destroys the ferment. J. P. L.

Comparative Estimation of Preparations of Pepsin. By A. A. LIPSKI (Russkaya Meditsina, 35, 583-584).—The powdered pepsins were examined by digesting 0-2 gram of the preparation with 10 grams of white of egg and 100 c.c. of hydrochloric acid (0.25 per cent.) for four hours at 40°. The undissolved albumin being then determined, the weight of this in grams was:-Perret acidifié 8.756, Marquart 8:577, Lamatch 8.557, Merck 7.213, Boudault neutre (No. 4) 2-62, Witte 2195, Boudault acidifié 1.2, Russicum solubile (of the Russian Ph.) 0·721, do. do. recent 047, do. do. without the sugar contained in the official preparation 0.157. The Russian pepsin is, therefore, far more active than any of the German or French preparations tested. The same holds good for the pepsin wines.

T. M.

Physiological Chemistry.

Sugar in the Blood with Reference to Nutrition. By J. SEEGEN (Pflüger's Archiv, 39, 121-131).-Experiments on dogs have shown (Abstr., 1886, 382 and 411) that the percentage of sugar is always approximately twice as great in the blood of the hepatic as in the blood of the portal vein during various carbohydrate diets and during long periods of inanition, also that peptone is probably the chief constituent from which the liver forms sugar under normal conditions. The sugar formed in one day during starvation is far in excess of the total glycogen present in the body.

Further experiments have been made on dogs fed with a diet of meat only, of fat with a minimal quantity of meat, and in some instances with fat only.

The general result is the same as in previous experiments, namely, that the percentage of sugar in the blood leaving the liver is double that of the blood on entering. The total amount of sugar in the blood as well as the difference between the percentages in the blood

on entering and leaving the liver is greater with a meat diet than any other.

The most striking result is the continued formation of sugar during an almost exclusively fat diet. It might be supposed that this is due to proteïd decomposition, but a determination of the nitrogen excreted during the feeding was quite insufficient to account for the increase.

The amount of blood passing through the liver of dogs of 10 to 12 kilos. is not less than 200 litres in the 24 hours. The mean difference in the percentage of sugar of the blood on entering and leaving the liver is 0.1 per cent., consequently about 200 grams of sugar would be formed in 24 hours. During the fat diet, the amount of nitrogen excreted daily was on an average 15 grams, corresponding to 100 grams of proteid, a quantity quite insufficient to furnish 200 grams of sugar, even supposing that none of the carbon of the proteïd be utilised for the formation of urea.

The conclusion drawn from these experiments is that the liver has the power of forming sugar from fat. This would satisfactorily explain the constant formation of sugar during starvation, for Voit has shown that an animal during starvation loses 97 per cent. of its fat, and only 30 per cent. of its muscular substance.

The chief results of the author's experiments may be thus summed up :

1st. The blood of the hepatic vein is without exception richer in sugar than the blood of the portal vein.

2nd. The new formed sugar does not depend on the sugar and carbohydrates ingested with the food.

3rd. The glycogen of the liver is not concerned in the formation of

sugar.

4th. Albumin and fat are the materials from which the liver forms sugar.

J. P. L.

Power of the Liver to Form Sugar from Fat. By J. SEEGEN (Pflüger's Archiv, 39, 132-142).-It has been previously shown that small pieces of freshly excised liver in the presence of defibrinated blood have the power of converting peptone into sugar (Abstr., 1886, 382). By a similar series of experiments, the author has proved that the liver cells can under the same conditions convert fat into sugar, thus confirming the conclusion he arrived at from his experiments on feeding dogs on a diet consisting exclusively of fat (preceding Abstract).

For each experiment, 50 grams of finely cut liver excised from a recently killed dog was mixed with 60 to 80 c.c. of freshly defibrinated blood and placed in a large flask; to this mixture various emulsions of vegetable oils were added. The flask and contents were maintained for 5 or 6 hours at 35° to 40°, and a constant stream of air was drawn through the mixture of blood by means of an aspirator. The average increase in the percentage of sugar was found to be 50 per cent. Control experiments were made in every instance.

A further series of experiments proved that both constituents of a fat, that is both glycerol and the fatty acid, are alike capable of being converted into sugar by the liver. J. P. L.

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