A text-book of physiological chemistry : for students of medicine and physicians / by Charles E. Simon.

  • Charles Edmund Simon
Date:
1904
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of physiological chemistry : for students of medicine and physicians / by Charles E. Simon. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    the substance is dissolved in concentrated sulphuric acid, the solution gradually assumes a purplish-red color, which changes to violet, and finally to brown. On adding an equal amount of water and l)oiling, a flocculent precipitate appears, which is known as cetylid, and is said to have the composition C^B[i2„0-g or (Ci6H3i02)3.[Ci6Hi8(OH)3]. This substance supposedly represents about 85 per cent, of the entire w^eight of the cerebrin. It is soluble in water, in hot alcohol, and especially in ether and chloroform. On fusion with caustic alkali, cetylid yields methane, hydrogen, and palmitic acid. Pure cerebrin is a colorless substance which occurs in the form of a crystalline powder, consisting of microscopical globulites. It is soluble in warm acetone, acetic ether, benzene, and boiling alcohol, but is insoluble in sulphuric ether, even at its boiling-point; with chloroform it forms an emulsion. In cold water it is likewise insoluble. In boiling water it swells to a certain extent, like starch paste. It melts at 177° C, but is decomposed long before with the development of a yellow or brownish color. Its reaction is neutral. Isolation.—Cerebrin can be obtained either from protagon after the separation of tlie latter or directly from the brain by decompos- ing its antecedents with baryta-water. To this end, the material after being freed from its membranes and blood is stirred with baryta-water, and brought to the boil. The insoluble portion is then pressed out and repeatedly extracted with alcohol by boiling. The extract is filtered while still hot, when on cooling to 0° C, the cerebrin separates out in impure form. It is freed from choles- terin and fats hy skakiug with ether, and purified by repeated solu- tion in hot alcohol and subsequent cooling, until jelly-like pre- cipitates, which are referable to homocerebrin or encephalin, are no longer ol)tained. With this method, however, a considerable portion of the cerebrin is decomposed, and Kossel has accordingly suggested that the protagon be first extracted and subsequently decomposed. To this end, the substance is dissolved in methyl alcohol, and is treated with a hot methyl alcoholic solution of barium hydrate. The mixture is w^armed for a few minutes on a water-bath, and then allowed to cool. The resulting precipitate contains the entire amount of •cerebrin which can be obtained, and re])resents 50 per cent, of the original quantity of protagon. It is filtered off, suspended in water, and freed from barium by a current of carbon dioxide. The insolu- ble residue contains the cerebrosides, which are now extracted with hot alcohol and isolated by fractional crystallization. Homocerebrin (Kerasin).—The formula of homocerebrin is given as CoHi.^X^Oi^, and the substance could hence be regarded as an anhydride of cerebrin. In the dry state it occurs as a wax-like mass, which can be pulverized only with difficulty. From its solu- tion in alcohol and boiling ether it separates out in aggregates of
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