310 Agricultural Chemistry. 



mixture, properly diluted, have proved valuable fungicides under 

 certain conditions. 



Formalin or formaldehyde, is a most efficient agent for destroy- 

 ing smut spores on grain. The seed should be immersed for ten 

 minutes in a solution of 1 pint of "40 per cent" formalin to 

 20 gallons of water. Stronger solutions have been found in- 

 jurious to the germinating power of barley. The seed should be 

 spread and finally mixed so as to dry with not more than two 

 to three hours contact with the formalin. 



Disinfectants are substances which accomplish the total de- 

 struction of the germs of infectious diseases. They may also act 

 as deodorants or destroyers of foul odors. 



Antiseptics prevent decomposition or putrefaction by arrest- 

 ing the development of germs, but do not necessarily destroy 

 them. Disinfectants in weak solutions may act as antiseptics. 

 Refrigeration, common salt and sugar, all of which are largely 

 used in preserving fruits, meats, etc., are good examples of anti- 

 septics. 



Formaldehyde is perhaps the most commonly used chemical 

 disinfectant. It is a product of the oxidation of wood alcohol 

 and is put upon the market in a 38 to 40 per cent solution in 

 water. A five per cent solution made from this should be mixed 

 with any solid matter to be disinfected. Gaseous formalde- 

 hyde is used for disinfecting inclosed" space and porous solid 

 matter in bulk. The gas should be delivered into a tightly closed 

 compartment in one of the following ways: Formalin may be 

 heated under pressure or in a simple retort and the gas piped 

 into the space; formalin may be sprayed upon sheets or other 

 extensive surfaces in the space to be disinfected and the gas 

 liberated by simple evaporation; six parts of formalin may be 

 poured upon five parts by weight of chemically pure potassium 

 permanganate. In the last case, heat is generated by chemical 

 reaction and 50 per cent of the formaldehyde is liberated as a 

 gas. Ten ounces of formalin are necessary for each 1000 cubic 



