398 CHEMISTRY OF THE PROTE1DS CHAP. 



large amounts of lysin and glutaminic acid. Its paranucleic acid (not 

 quite free from albumin) contains, according to Willdenow 1 and 

 Salkowski, 2 3 to 4 per cent of phosphorus. 



The iodine-caseinogens are discussed on p. 231 ; the chlorine- 

 caseinogens of Habermann and Panzer and the nitro-substitution- 

 product of v. Fiirth on p. 236. 



Free caseinogen is quite insoluble in water, while its salts are 

 very readily soluble. Osborne 3 has shown that caseinogen being 

 an acid substance, forms two distinct groups of salts. The first group 

 includes the salts of Ca, Mg, Ba, and Sr, and the salts of strong 

 organic bases such as caffein and strychnin ; all these produce markedly 

 opalescent solutions, are unable to pass through the pores of a clay 

 filter, and are precipitated from their solutions by the addition of 

 insoluble finely divided substances. They are acted upon by rennin, 

 and on heating form a haptogen - membrane. On warming their 

 solutions a turbidity occurs between 35 and 45, which disappears 

 on cooling. This phenomenon is explained as due to hydrolysis 

 occurring as the result of heating, according to fhe equation : 



Calcium caseinogenate + 2H 2 = Ca (OH) 2 + caseinogen. 



The second group contains the salts of K, Na, and NH 4 . These 

 form comparatively clear solutions ; pass through clay-filters ; are not 

 precipitated by the addition of finely divided substances ; are not 

 visibly altered on heating ; do not form a haptogen-membrane ; and 

 are not acted upon by rennin. 



Caseinogen, being an albuminous substance, resembles the other 

 albumins in also being able to form salts with acids, and is therefore 

 readily soluble in the presence of an excess of an acid, but notwith- 

 standing this it is essentially an acid substance. In its salts with 

 bases it has an equivalent weight of 1135, and is at least 4 to 6 

 basic according to Laqueur and Sackur. 4 The much higher equiva- 

 lent weights of 5000 to 6000 calculated from the figures of Salkowski, r> 

 Hammarsten, Lehmann and Hempel, 7 and Soldner, 8 are partly due 

 to hydrolysis and partly to acid salts having been investigated. 



spondenzblatt f. Schuvizer Arzte, 1903, No. 22 ; L. Blum, Zeitschr. f. physiol. C% ////. 30. 

 15 (1900) ; E. Beudix, Archivf. (Anat. nnd) Physiol. 1900, Suppl. p. 309. 



1 C. Willdenow, Dissertation, Bern, 1893. 



2 E. Salkowski, Zeitschr. f. physiol. Chem. 32. 245 (1901). 



3 W. A. Osborne, Journ. of Physiol, 27. 398 (1901). 



4 E. Laqueur and 0. Sackur, Hofmeister's Keitrdge, 3. 193 (1903). 



5 E. Salkowski, Zeitschr. f. Biol. 37- 401 (1899). 



6 O. Hammarsten, Konigl. Gesellschaft der Wissenschaften zu Upsala, 1877. 



7 W. Hempel, Pjlligers Archivf. d. </es. Physiol. 56. 558 (1894). 



8 F. Soldner, Dissertation, Erlangen (1888). 



