212 MODES OF PRESERVING MILK. 



This form of the lactometer was invented by Sir Joseph 

 Banks. 



Various means are used for the preservation of milk. 

 One of these is by concentrating it by boiling. Where 

 this is followed, as it is by some dairymen, as a regular 

 business, the milk is poured, as it comes from the dairy, 

 into long, shallow, copper pans, and heated to a temper- 

 ature of a hundred and ten degrees, Fahrenheit. A lit- 

 tle sugar is then mixed in, and the whole body of milk 

 is kept in motion by stirring for some three or four 

 hours. The water is evaporated, leaving the milk about 

 one fourth of its original bulk. It is now put into tin 

 cans, the covers of which are soldered on, when the 

 cans are lowered into boiling water. After remaining 

 a while, they are taken out and hermetically sealed, in 

 which condition the milk will keep for months. Con- 

 centrated milk may thus be taken to sea or elsewhere. 

 Another form is that of solidified milk, in which state it 

 is easily and perfectly soluble in water ; and when so 

 dissolved with a proper proportion of water, it assumes 

 its original form of milk, and may be made into butter. 

 A statement by Dr. Doremus, in the New York Medical 

 Journal, explains the process, as follows : 



To one hundred and twelve pounds of milk twenty 

 eight pounds of Stuart's white sugar were added, and a 

 trivial portion of bicarbonate of soda, — a teaspoonful, 

 — merely enough to insure the neutralizing of any acid 

 ity, which, in the summer season, is exhibited even a 

 few minutes after milking, although inappreciable to 

 the organs of taste. The sweet milk was poured into 

 evaporating pans of enamelled iron, imbedded in warm 

 water heated by steam. A thermometer was immersed 

 in each of these water-baths, that, by frequent inspec- 

 tion, the temperature might not rise above the point 

 which years of experience have shown advisable. To 



