i MILK 115 



,/: = quantity f added water. 



y = abstracted cream, expressed in the amount of fat 



removed from 100 parts of milk. 

 r = solids not fat in the stall sample. 

 r' = suspected sample. 

 w = percentage amount of water in the stall sample. 

 w' = suspected sample. 



f = fat in stall sample. 

 /' = suspected sample. 



It need hardly be mentioned that analyses of this description 

 only have a legal value when they are made by fully competent 

 persons, and the greatest care exercised both in the actual 

 analyses and in the taking of the samples of milk. 



IV. ADMIXTURE WITH GOAT'S MILK. 



In some districts cow's milk is occasionally mixed with small 

 quantities of goat's milk, a process which must be regarded as 

 falsification if the purchaser is not aware of it. 



R. Steinegger 1 has worked out a simple method for dis- 

 tinguishing between cow's and goat's milk, and for proving the 

 addition of large quantities of the latter to the former. 



Steinegger found that when 25 per cent, ammonia is added 

 to goat's milk there is a precipitation of protein material which 

 does not occur with cow's milk, because the casein from cow's 

 milk goes into solution. 



Twenty c.c. of milk are heated to 50 C. and allowed to 

 stand at this temperature. Then 2 c.c. of ammonia (25 per 

 cent.) are added, and the whole well shaken, the shaking being 

 repeated each half-hour or hour for two or three hours. At the 

 end of this time a layer of protein matter has formed under 

 the layer of cream, although the protein is specifically heavier 

 than the milk. The reason of the protein substances being 

 there is because they have been carried up by the rapid rising 

 of the cream. If such a precipitation has formed, it is evidence 

 that the milk is from the goat, or is cow's milk largely mixed 

 with goat's. 



Where the milk contains about 20 per cent, of goat's milk, the 



1 Landwirtichaftliches Jahrbuch der Schweiz, 1904. 



I 2 



