LITMUS WHEY 



195 



Whey Gelatine. 



1. Curdle fresh milk by warming to 60 C., and adding rennet; 

 filter off the whey into a sterile "tared" flask. 



2. Estimate and note the reaction of the whey. 



3. Weigh out gelatine, 10 per cent., and add it to the whey 

 in the flask. 



4. Bubble live steam through the mixture fifteen minutes to 

 dissolve the gelatine; and weigh. 



5. Estimate the reaction of the medium mass; then add 

 sufficient caustic soda solution to restore the reaction of the 

 medium mass (i.e., total weight minus weight of flask) to the 

 equivalent of the original whey. 



6. Cool to 60 C. and clarify with egg as for nutrient gelatine 

 (vide page 166). 



7. Filter through papier Chardin. 



8. Tube, and sterilise as for nutrient gelatine. 



Whey Agar. 



1. Curdle fresh milk by warming to 60 C., and adding rennet; 

 filter off the whey into a sterile flask. 



2. Weieh out agar, 1.5 or 2 per cent., and add it to the whey 

 in the flask. 



3. Bubble live steam through the mixture for twenty minutes, 

 . to dissolve the agar. 



4. Cool to 60 C. ; clarify with egg as for nutrient agar (vide 

 page 1 6 8). 



5. Filter through papier Chardin, using the hot-water funnel. 



6. Tube, and sterilise as for nutrient agar. 



Litmus Whey. 



1. Curdle fresh milk by warming to 60 C. and adding rennet. 



2. Filter off the whey through butter muslin into a sterile flask. 



3. Neutralise to litmus by the cautious addition of citric acid 

 solution 4 per cent. (Do not neutralise with mineral acid.) 



4. Heat in the steamer at 100 C. for one hour to coagulate all 

 the proteid. 



(If the whey is cloudy when removed from the steamer allow 

 it to stand for forty-eight hours in the ice chest and then decant 

 off the clear fluid or filter through a Berkfeld filter candle.) 



5. Filter into a sterile flask. 



6. Tint the whey with litmus solution to a deep purple red. 



7. Tube, and sterilise as for milk. 



Litmus Whey (Petruschky). 



i. Measure out into a flask 



Fresh milk 1000 c.c. 



