1913.] 



Phenomena of" Clot " Formations. 



469 



acid, from which, on heating, the elements of water are removed from 

 contiguous hydroxyl groups. On treatment with caustic alkalis, and 

 acidification of the alkaline solution, these elements are added again to the 

 molecule, which is thereby enabled to again form the poly-acid. The 

 relationship, if this view is correct, is similar to that existing between a 

 pyrophosphate and a metaphosphate, a conception which is not improbable 

 when it is remembered that caseinogen is a derivative of phosphoric acid. 



Physically there is a marked difference between the saturated solutions 

 (i.e. as regards caseinogen) of the calcium salts (containing the same amount 

 of calcium) of caseinogen and metacaseinogen. The former are white 

 opaque solutions which retain their opacity even after considerable dilution, 

 whereas the latter (produced by the prolonged action of water at 37° on 

 natural caseinogen) are translucent, although opalescent. 



It may be recalled here that these tw T o forms are readily convertible, one 

 into the other. As might be expected, the nitrogen-phosphorus ratios 

 remain constant. The analyses of the various products are not quoted in 

 this paper. They are also neutralised by the same amount of sodium 

 hydroxide. 



The Action of Calcium Salts on Solutions of " Natural " Cascinogenates. 



Throughout all the following experiments a saturated solution of " natural " 

 caseinogen in \ sat. Ca(OH) 2 (10 c.c. = 2T5 c.c. N/10 acid) and equimolar 

 carbonate-free sodium hydroxide (20 c.c. = 2T5 c.c. X/10 acid) have been 

 employed. The solutions were always prepared by gentle rotation for 

 17 hours in a thermostat of 4 grm. of caseinogen with 40 c.c. of the alkaline 

 solution. The mixture was afterwards centrifuged for two hours at a speed 

 of 3500 revolutions per minute, and the supernatant fluid decanted off. 



Action of Calcium Chloride Solutions on Sodium Caseinogenate Solutions. — 

 "When the caseinogenate solutions are treated with calcium chloride, a pre- 

 cipitate is formed, but only within certain limits of the concentration of 

 the calcium salt. The reactions form therefore an " irregular series," a 

 phenomenon which is not uncommon when a reacting substance is a complex 

 colloid.* 



In the following experiment 10 c.c. of the sodium caseinogenate solution 

 were diluted with 10 c.c. of calcium chloride solutions of varying strengths. 

 After standing, the mixtures were filtered through folded filter-papers, and 

 the nitrogen was estimated in 10 c.c. of the filtrate. The results are given 

 in the following table : — 



* These reactions are discussed in some detail in a footnote to a former paper (' Roy. 

 Soc. Proc.,' 1910, B, vol. 83, pp. 97 and 98). 



