570 CONTRIBUTION TO OUR KNOWLEDGE OP THE ACTION OP RENIN, 



of milk of different degrees* of acidity was very constant. Thus, 

 though the acidity of differen t samples of milk varied from 1 2 D -20°, 

 the same quantity of soda (0-4 c.c. j^NaOHto 5 c.c.milk) prevented 



Table ii. 

 Acidity of milk, 16-8°. 



Tube. 



Milk. 



■&NaHO. 



Water. . 



Eennet. 



Eesult. 



1 



5 c.c. 







1 c.c. 



1 c.c. 



Clotting in 13 min. 



2 





0-1 c.c. 



0-9 c.c. 





29 „ 



3 





0-2 c.c. 



0-8 c.c. 





3S „ 



4 





0-3 c.c. 



0-7 c.c. 





82 ,, 



5 





0-4 c.c. 



0'6 c.c. 





No clotting. . 



6 



, 



0-5 c.c. 



0-5 c.c. 





,, 



7 



, , 



0-6 c.c. 



0-4 c.c. 





,, 



8 



? > 



0-7 c.c. 



0-3 e.c. 





5) 



clotting. This is dependent upon the quantity of mono-h} T drogen 

 and di-hydrogen phosphate present in the milk. Further, as will 

 be shewn in a later paper, the measure of the acidity of milk is 

 not the measure of the lactic acid present, and the acidity of 

 milk is not that of the lactic acid formed by fermentation from 

 lactose. If the quantity of soda was kept constant in a series 

 of tubes in which the amount of rennet was varied, the time of 



Table iii. 



100 c.c. milk received 2 -8 c.c. T N 7 NaOH. 



Acidity of milk then 12°. Each tube contains 5 c.c. milk. 



Tube. 



Eennet. 



Time of Clotting. 



1 

 2 

 3 



0-1 c.c. 

 0-2 c.c. 

 0-3 c.c. 



33 min. 

 22 nain. 

 19 min. 



clotting diminished as the rennet was present in larger quantity, 

 provided always that clotting occurred at all. Such a series is 

 recorded in Table iii. 



* It is customary to denote the number of cubic centimetres of decinormal 

 soda required to neutralise 100 c.c. milk as so many degrees of acidity. 



