264 § 136. FODDER AND FOOD. 



in the case of some diseases, it occurs in larger quantity. 

 To estimate it, coagulate 100 grms, of the milk with ren- 

 net, at a temperature of about 45° C, filter out the pre- 

 cipitate, and wash it, and heat the filtrate and washings 

 to boiling. Collect the precipitated albumen on a dried 

 and weighed filter, dry it at 100 C, and weigh it. 



d. Butter. — Extract the residue obtained in a with 

 ether (§ 87). 



Various other and shorter processes are given for tes-t- 

 ing the goodness of milk in this respect, in one of which 

 the cream is estimated by volume. 



Provide a shallow glass dish in the form of an inverted 

 bell-jar, with a ground glass plate to cover it and prevent 

 evaporation of the milk, and a narrow orifice below, closed 

 with a glass stopper ; a graduated cylinder holding 100 

 c.c. will also be needed. 



Put 100 c.c. of cooled milk into the dish, and let it stand 

 24 hours, at a temperature of 12-15° C. ; then loosen the 

 stopper below, and let the milk flow out from underneath 

 the cream into the graduated cylinder. After about ^ |^ 

 of the milk has run out, stop the flow for a few minutes, 

 to allow the cream to collect together somewhat, and then 

 let the milk flow out again, but only drop by drop, until 

 the cream appears at the opening ; the quantity by which 

 the milk now collected in the cylinder is less than the 

 original 100 c.c. represents the cream, and the percentage 

 of cream by volume can be estimated. 1"! ^ by volume 

 corresponds very nearly to one-fourth °|o of butter in the 

 milk, by weight. 



If a glass dish, like that described above, cannot bo 

 obtained, any shallow dish that can be Avell covered will 

 answer, and the milk can be withdrawn from under the 

 cream by a small siphon, with a rubber tube and clamp 

 at the end of the longer arm to regulate the flow of the 

 liquid. 



