400 AGRICULTURAL BACTERIOLOGY. 



method of disinfection should remember. In case of con- 

 tagious diseases the excretions eliminated from the infected 

 animal are practically certain to contain the infectious organ- 

 isms. Hence disinfection in such cases must be primarily di- 

 rected towards destroying such excretions, and in preventing 

 them from being distributed from animal to animal by any 

 possible means. One cannot go far wrong, in his application 

 of disinfectants, if he makes his primary effort that of destroy- 

 ing the bacteria possibly present in the excretions from suffer- 

 ing animals. 



2. The next problem is the selection of a disinfectant. It 

 is manifest that different disinfectants must be used under dif- 

 ferent conditions. The comparatively harmless formalin can 

 be used where the poisonous corrosive sublimate would be out 

 of the question. For example, formalin has been used for the 

 preservation of milk, one teaspoonful being sufficient to in- 

 crease greatly the keeping qualities of ten gallons of milk ; 

 when used in this quantity formalin does not produce any no- 

 ticeable results, at least at first, upon the person drinking the 

 milk. The use of the other disinfectants, corrosive sublimate 

 or carbolic acid, would be manifestly impossible in these cases. 

 But on the other hand, formalin is a material extremely irritat- 

 ing to the nose, and very irritating to mucous membranes and 

 raw surfaces generally. Formalin, therefore, though less poi- 

 sonous than carbolic acid, cannot be used in surgery, and can- 

 not be used in any place where the gas becomes abundant 

 enough to be irritating. For every case, then, the disinfectant 

 must be chosen which is most applicable. 



A very few suggestions for disinfection may be given as 

 likely to be of practical value to the agriculturist. 



The Person. When it is desired to disinfect the person, 

 either of man or of animals, the common disinfectant used is 

 corrosive sublimate in proportion of I to 1,000, or carbolic 

 acid in proportion of I to 20. These may be used freely upon 



