266 § 136. FODDER ATSTD FOOD. 



watered. It is rare that less than 3 c.c. of cow's milk will 

 be needed. 



e. Sugar. — Collect the residue, insoluble in ether, in d^ 

 on a dried and weighed filter, dry it at 100° C, boil it four 

 or five times with fresh portions (150 c.c. each) of 80" l^ 

 alcohol, and weigh this insoluble residue on a dried and 

 weighed filter, after drying it at 100° C. The loss of 

 weight, after extraction with alcohol, gives the lactose 

 approximately. The residue on the filter will be mainly 

 casein and insoluble salts, together with the baric sul- 

 phate or gypsum, with which the milk was evaporated. 



Or, to determine the lactose more accurately, dilute 20 

 grms. of the milk with twice its volume of water, heat 

 the liquid to 40° C, coagulate the casein with 4 drops of 

 acetic acid, collect the coagulum on a linen filter,- and 

 wash it well with water. Dilute the filtrate and washings 

 to 200 c.c, and determine lactose in the usual manner, in 

 a measured volume of the liquid, previously filtered if 

 necessary (§ 84). 



f. Lacto-protein, butter , casein^ etc. — Millon and 

 Commaille give this process for estimating the protein 

 compound peculiar to milk, and for the determination of 

 other substances also. 



Dilute 20 grms. of milk with 4 volumes of Avater, add 

 5-6 drops of acetic acid, stir the mixture well, filter out 

 the coagulum, wash it two or three times on the filter with 

 a^ little water as possible, and then with 40" („ alcohol. 

 Separate the precipitate from the filter, difinse it in abso- 

 lute alcohol, collect it again on a dried and weighed filter, 

 and extract the butter by ether containing ^\^^ of abso- 

 lute alcohol, that is poured over the contents of the filter. 

 Evaporate the etherial extract, to estimate the butter taken 

 into solution, and dry the casein on the filter at 100° C, 

 and weigh it. 



Heat half the filtrate from the first coagulum, or the 



