1913.] 



Phenomena of" Clot " Formations. 



±77 



Experiments were next 'carried out to ascertain whether the treatment 

 with alcohol had caused the difference between the calcium chloride and the 

 rennet clots. For this purpose a calcium chloride clot was obtained in the 

 form of a dry powder, by the method described above, and then boiled for 

 10 minutes with alcohol, and purified by solution in alkali and repre- 

 cipitated. The preparation thus obtained also gave with \ sat. Ca(OH) 2 an 

 opaque solution of high concentration (29 - 7) which did not clot on addition 

 of rennet, and gave only an incomplete clot on addition of calcium chloride. 

 Alcohol, therefore, alters both the calcium chloride and the rennet clots. 

 The fact may be recalled that caseinogen on heating with alcohol is not 

 altered, but yields a solution in \ sat. Ca(OH) 2 , which readily clots both on 

 addition of rennet and calcium chloride. The clot produced by calcium 

 chloride alone, however, on re-solution in alkali, is readily converted into 

 caseinogen, whereas the clot produced by rennet alone, even after redis- 

 solving in alkali, yields a product of low solubility in \ sat. Ca(OH) 2 from 

 which no clot could be produced. It was unfortunately necessary to heat 

 the rennet clot with alcohol to destroy the ferment, and as there is evidence 

 that the calcium chloride clot is also altered by this treatment, the question 

 as to whether the rennet clot can be reconverted into a clottable caseinogen 

 remains for the present unsolved. 



Numerous other experiments were carried out with the object of preparing 

 a clottable calcium caseinogenate solution from the rennet clot. The 

 ferment in one experiment was destroyed by heating with water, and then 

 after drying with alcohol and ether was redissolved in sodium hydroxide 

 solution and reprecipitated by acid. In another experiment the clot, after 

 washing with ice-cold water, was directly dissolved (whilst still moist) in 

 sodium hydroxide solution, reprecipitated, dried in the usual way, and then 

 heated for a few minutes with boiling alcohol, a treatment which causes no 

 change in caseinogen. In no case was a product of greater solubility than 

 17 to 20 in \ sat. Ca(OH) 2 obtained, which is only about half that of natural 

 caseinogen. The solutions were in all cases translucent and yielded no clot 

 either with calcium chloride or with rennet. The evidence obtained so far 

 tends to indicate that rennet alters caseinogen in such a way that it is not 

 inconvertible into caseinogen. 



The fact that both descriptions of clot are altered by alcohol, whereas 

 caseinogen is not, indicates that the latter undergoes some change during the 

 process of clot formation. The fact, however, that the rennet clot, even after 

 re-solution in alkali, gives a product of low solubility in lime water, whereas 

 the calcium chloride clot gives one of high solubility (even after treatment 

 with hot alcohol), indicates that the caseinogen under the influence of rennet 



2 N 2 



