BY A. H. MOSELBY AND H. G. CHAPMAN. 



575 



been shown by numerous investigators, Maly,* Lorcher,f Ham- 

 marsten,j Ringer,§ Langley,|| and Boas,1T that small quantities of 

 free caustic soda rapidly destroy rennin. This destruction is 



Table xi. 

 Acidity of milk, 188 Q . 

 5 c.c. milk in each tube. 0"15 c.c, rennet in each tube. 



Tubes. 



T N oNa 2 HP0 4 



Result. 



1 



— Clotl 



ing in 31 min. 



2 



0-1 c.c. 



43 „ 



3 



0-2 c.c. 



59 , 





4 



03 c.c. 



59 , 





5 



0-4 c.c. 



59 , 





6 



0-5 c.c. 



70 , 





7 



0-6 c.c. 



74 , 





8 



0-7 c.c. 



76 , 





produced by the hydroxyl ions which result from the dissociation 

 of the soda. If there were present in the milk to which caustic 

 soda had been added free hydroxyl ions, destruction of rennin 

 would occur. If the rennin had been destroyed, it would not be 

 possible to produce clotting of this milk after the conditions of 

 the milk had again been made favourable to clotting. On the 

 other hand, if rennin were still present, the establishment of a 

 favourable environment should produce clotting. It was found 

 that the addition of neither hydrochloric acid, nor hydrochloric 

 acid and calcium chloride, nor fresh milk, hydrochloric acid 

 and calcium chloride, produced clotting after the milk and 

 soda had been in contact for four hours. If, however, the 

 quantity of y^NaOH was not great, the addition of these sub- 

 stances sometimes produced clotting. Some typical experiments 

 are recorded in Table xii. 



* Quoted in article ' Estomac,' Eichet, Diet. Physiol., Paris, 1902, t.v., 

 p.6SS. 



t Arch. f. d. g. Physiol., Bd.lxix., s.141, 1S98. 



t Maly's Jahrb., 1874. 



§ Journ. Physiol., Vol.xi., 1890. 



|| Journ. Physiol., Vol.iii., p.287, 18S0-2. 



1 Zeitschr. f. klin. Med., Bd.xiv., s.249, 1SS8. 



