31G Third Annual Report of the > 



To the remaining half of the distillate is added about one 

 cubic centimeter of a solution of fuchsin, which has been decolor- 

 ized with sulphurous acid, the tube carefully stopped and set 

 aside for two hours,, at the end of which time the solution will 

 have taken on a pink tint, if formic aldehyde is present. 



In order to ascertain whether a pure milk would yield a distil- 

 late having a reducing action on the silver or fuchsin solution, 

 and also whether the addition of some of the common preserva- 

 tives, as boric acid, or sodium carbonate, might not give such a dis- 

 tillate, the following experiments were performed : The milk used 

 in these experiments was obtained direct from the animal, so that 

 there can be no question as regards its purity. 



First. A sample of pure milk was distilled and the distillate 

 divided into two portions. To one portion was added six drops of 

 the silver solution and to the other some fuchsin solution. The 

 portion to which the silver nitrate solution had been added, took 

 on a brownish tint, but gave no precipitate, while the fuchsin 

 solution remained unchanged. This experiment was repeated 

 with several different samples of milk with the same results. 



Second. To a sample of pure milk was added salicylic acid, so 

 that it was contained in the milk in the proportion of Gl grains 

 to the gallon. After this sample had stood for 36 hours it was 

 distilled and tested as mentioned. The results were negative even 

 after they had stood several days. 



Third. To another portion of the milk boric acid was added in 

 the proportion of 12 grains per gallon. After standing 24 hours 

 this sample was distilled and the distillate tested as already 

 mentioned. At the end of 12 hours the silver nitrate solution 

 showed a slight brownish-black precipitate; the other solution 

 showed no reaction. 



Fourth. To another portion of the milk sodium carbonate was 

 added in the proportion of 18J grains per gallon. That portion of 

 the distillate to which the silver nitrate solution had been added, 

 gave a slight brownish precipitate in 12 hours. 



Fifth. Milk, to which formal had been added in different pro- 

 portions was next examined. A sample of milk containing 



