110 DAIRY LABORATORY GUIDE 



Wyandotte Dairyman's Cleaner and Cleanser 1 to 

 20; Banner Purifying Compound 1 to 20; borax 1 

 to 20; sal. soda 1 to 20; Fairbanks' washing powder 

 1 to 20; Tessico washing powder 1 to 20; gold dust 

 1 to 20; powdered unslaked lime 1 to 20; powdered 

 gypsum 1 to 20. Use and note results. Gypsum is 

 preferable to lime in barns or on any material which 

 may afterwards be used for fertilizer, for the latter 

 forms soluble salts with the nitrogen of manure and 

 liberates a large per cent of the ammonia present. 

 (NH 4 ) 2 C0 3 + CaO 2NH 3 + CaC0 3 + H 2 0. 

 (NH 4 ) 2 S0 4 + CaO == 2NH 3 + CaS0 4 + H 2 0. This 

 causes a loss of valuable fertilizer and produces an 

 offensive odor which milk readily absorbs. Gypsum, 

 on the other hand (CaS0 4 ), is insoluble with the 

 nitrogen of manure and is retained until deposited 

 in the fields. 



EXERCISE XXXII 



MECHANICAL REFRIGERATION 



If refrigerating machinery is in use at the college, 

 note the kind of machine, whether vacuum, absorp- 

 tion, compression, or combined absorption and com- 

 pression. Note principle of refrigeration which is 

 the production of cold air by the evaporation of liquids 

 which absorb the heat in vaporizing. Anhydrous 

 ammonia is generally used on account of its low 

 boiling point. It liquifies at 30 F. under one atmos- 

 pheric pressure. It liquifies at higher temperatures 

 by subjecting it to pressure. It is alternately evap- 



