206 REPORT OF ‘THE CHEMIST OF THE 
In preparing the sterilized rennet solution, we diluted 5 cc 
of Hansen’s rennet-extract to 25 ce. with water, added 5 per 
ct. of formalin, proved the completeness of sterilization by 
bacteriological examinations, diluted to 100 cc. and added 10 
cc. of this preparation to each flask containing cheese. 
The flasks thus prepared were kept at 60° F. (15.5° C.). The 
analytical results given below were obtained at the end of two 
and four weeks. In this work we had only the enzymes of 
pepsin and of rennet-pepsin acting upon our proteid. Under 
these conditions, especially in the given length of time, we 
should not expect the formation of any considerable amount of 
amido-acid compounds precipitable by phosphotungstic acid. 
The results obtained are given in the following table: 
TaBLE II].—CoMPARISON oF PHOSPHOTUNGSTIC ACID AND TANNIN- 
SALT SOLUTION IN PRECIPITATING THE NITROGEN COMPOUNDS 
ForMEpD BY PEepric DIGESTION OF CHEESE. 


| PERCENTAGE OF NITROGEN IN CHEESE FOUND IN FILTRATE 
AFTER PRECIPITATION BY— 

{ 


No. of sample... rod 2 M 3 | 4° /)°5 6 7 | 8) | Ave. 
Phosphotungstic acid.. 0.10 0.10)0.150 00. 175 0.10 0. 08 0.16, 0. 160. 128 
Tannin-salt solution... .| 0.45) 0.44.0. 0.645'0.685 0. 48) 0.46) 0.73] 0. sbi 574 
| 


In every case except one the amount of nitrogen not precipi- 
tated by tannin-salt solution was more than four times the 
amount obtained by phosphotungstic acid. No ammonia was 
present in any case. In view of these widely differing results 
in relation to the amounts of amido-acid compounds found, the 
questions may be asked: Which reagent more nearly repre- 
sents the amount of amido compounds actually present? Does 
the tannin-salt reagent fail to precipitate the peptones com- 
pletely, thus allowing the unprecipitated peptones to be counted 
among the amido-acid compounds? Or does the amount: of 
nitrogen in the filtrate in case of this reagent really represent 
amido-acid compounds? Does the phosphotungstic acid pre- 
cipitate some of the amido-acid compounds simultaneously with 
