APPENDIX V 311 



the effluent may be transferred to some other vessel 

 for boiHng. 



After boiling, the fluid may be safely used for fer- 

 tiHzer under any conditions. 



Heat disinfection is the only measure which can to- 

 day be recommended unreservedly. 



(2) Burial: Burial will unquestionably decrease the 

 dangers of spreading infection, but in the present state 

 of our knowledge this method of disposal cannot be 

 relied upon as safe. If burial of the effluent is prac- 

 tised, the fluid should be disposed of not less than 300 

 feet from and downhill from any neighboring water 

 supply and not less than two feet underground, and 

 then only provided the soil itself is a good filter. Bur- 

 ial in a limestone region may contaminate water sup- 

 plies miles away. 



(3) Chemical disinfection: Chemical disinfectants, 

 such as chlorinated lime and certain coal-tar deriva- 

 tives, have the great advantage of cheapness and can 

 be relied upon to destroy pathogenic bacteria. Our 

 knowledge regarding the action of chemical disinfec- 

 tants upon the eggs and spores of the various animal 

 parasites is at present very rudimentary, but so far as 

 results are known, their practicable use does not seem 

 to be so efficient in the destruction of the zooparasitic 

 as of the bacterial infectious organisms. Therefore, 

 pending further investigations, the use of chemically 

 treated excrement as fertilizer should not be regarded 

 as unqualifiedly safe. 



(4) Chemical disinfection with subsequent burial : 



