Commissioner op Agriculture. 317 



2 28-100 grains per gallon was allowed to stand 12 hours and then 

 subjected to distillation. The distillate was treated with silver 

 nitrate solution; at the end of 12 hours a beautiful mirror had 

 formed on the surface of the test tube. This sample was not 

 tested with fuchsin solution. 



Another portion of milk, to which formic aldehyde was added 

 in the proportion of 1 14-100 grains per gallon, gave a distillate 

 which, upon treatment with silver nitrate solution, took on a 

 brownish-black color in a few hours, but gave no precipitate. 

 With the fuchsin solution a pink tint was developed within two 

 hours. Another portion of milk, to which formic aldehyde had 

 been added in the proportion of one-half grain to the gallon, gave 

 no reactions upon treatment of its distillate. 



In order to ascertain whether the formic aldehyde could be 

 detected in a sample after it had become sour^ the milk containing 

 2 28-100 grains of formic aldehyde to the gallon was allowed to 

 sour, and then subjected to distillation. The distillate^ divided 

 into two portions and treated with silver nitrate and fuchsin 

 solution, in neither case did any reaction take place. 



What is the Relative Value of this Formalin as a Preserva- 

 tive as Compared With Other Preservatives? 



R. T. Thomson (Ghem. News, 1895) says that 8f grains per 

 gallon of formic aldehyde is as effective as 35 grains of salicylic 

 acid, or 35 grains of boric acid, half as free acid, half as borax, 

 and that it surpassed 35 grains of free boric acid, or 17^ grains 

 of benzoic acid. 



My own experiments show that 2 28-100 grains of formic alde- 

 hyde per gallon were as effective as 61 grains of salicylic acid, 

 and more effective than 12 grains of boric acid. 



The physiological effect produced by the continued use of formic 

 aldehyde upon the animal economy is as yet unknown and, there- 

 fore, nothing can be said upon that point. 



It is not at all improbable that the use of formalin, not alone 

 for the preservation of milk, but of other food stufifs as well, will 



