Volume 1

Animal chemistry : with reference to the physiology and pathology of man / by Franz Simon ; translated and edited by George E. Day.

  • Simon, Johann Franz, 1807-1843.
Date:
1845-1846
Catalogue details

Licence: Public Domain Mark

Credit: Animal chemistry : with reference to the physiology and pathology of man / by Franz Simon ; translated and edited by George E. Day. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    45/430 (page 21)
    applied cautiously, as casein is soluble in an excess of many acids. On the addition of ferrocyanide or ferridcyanide of potassium to a perfectly neutral solution of casein, a slight precipitate is observed; if the solution is alkaline there is no perceptible effect, but if it is first rendered acid by a little acetic or dilute sul- phuric acid, a copious precipitate is thrown down by both tests. The casein of cow^s milk is thoroughly precipitated by the mucous membrane of the calf s stomach; on the addition of this reagent to woman’s milk, imperfect coagulation sometimes oc- curs ; in other cases no apparent action is produced; the coagu- lation is never perfect. In this case the mucous membrane of the child’s stomach produces a more energetic effect than that of the calf. If a qiiantity of potash or ammonia be added to the milk, sufficient to give it a decidedly alkaline reaction, no coagulation is effected. Rochleder has recently attempted to show that pure casein is a substance nearly insohible in water; that the so-called soluble casein is a combination of casein with potash, soda, or lime; and that the coagulation of the soluble casein by acids is nothing more than a separation of the casein, resulting from the combination of the acid with the base of the casein com- pound. In this manner, he explains how solutions of potash prevent coagulation, when added in very small qnantity to milk, and why (especially in warm weather) very slight causes are able to produce a coagulation of the milk; as only the smallest quantity of lactic acid is required to be formed, in order to neutralize the minute traces of soda, which are able to retain in a state of solution an enormous quantity of casein. Xoagulated casein is found in the milk, constituting the walls of the butter-vesicles. For the purpose of chemical investiga- tion, it is best obtained by the addition of anhydrous alcohol to a solution of casein. When dried, it is hard, yellow, and transparent. In its chemical relations it closely resembles coagu- lated albumen. The amount of ash left after the incineration of casein seems to vary considerably. Mulder estimates it at 3‘82, and Simon at 7%, in the casein of cow’s milk. In casein from the milk of woman, Simon estimated it at 5g. liochleder, whose experi- ments wei’e made under the direction of Liebig, found that pure