52 PRACTICAL AGRICULTURAL CHEMISTRY [142-144 



salt with a little water. The curd may be shown to contain 

 nitrogen by heating with soda-lime as described in para- 

 graph 85. 



142. Salt in Butter. — Hold the greasy filter-paper 

 prepared in the last experiment, together with its contents, 

 by means of a pair of crucible tongs over a porcelain tile, 

 then light it with the flame of a Bunsen. When it has 

 quite burned, and the ash has fallen on to the tile, sweep it 

 up into a test-tube. Half fill the test-tube with water and 

 boil for a minute or two, then filter. The clear liquid which 

 comes through will contain any salt which was present in 

 the original butter. To test for salt add a drop of dilute 

 nitric acid and a few drops of silver nitrate solution. A 

 white precipitate will be formed (see paragraph 201). 



Cheese 



Cheese contains exactly the same constituents as butter, 

 but in different proportions. Thus whilst the butter consists 

 principally of fat the cheese consists chiefly of curd. 



143. Fat in Cheese. — Place a few cheese-parings on 

 a piece of filter-paper and heat in the steam-oven (22). The 

 fat in the cheese will melt and grease the paper. 



144. Albuminoids in Cheese.— Heat a little of the 

 cheese with soda-lime as described in paragraph 85. The 

 presence of nitrogen is shown by the evolution of ammonia. 



