320 INORGANIC AGENTS 



pervious material. StilJ, formaldehyde is the best practical 

 disinfectant now known for the sterilization of infected pre- 

 mises. It is as yet comparatively expensive. The gas is 

 most effective between 60^ and 70° F., but will act at other 

 temperatures. It is nof so operative in damp air, and the 

 premises should be closed tight from the outer air, in order 

 that the disinfection may be thorough. One-half a liter 

 (about one pint) of pure wood alcohol will yield a 2J per 

 cent, formaldehyde atmosphere in 1,000 cubic feet of air 

 space, and this is the proper proportion of alcohol necessary 

 for disinfection. The premises containing the gas should 

 be sealed from 4 to 24 hours. Formaldehyde vapor is 

 extremely pungent and irritating to the mucous membranes, 

 causing running of the nose and eyes in those exposed to 

 its influence ; but some experimenters have subjected ani- 

 mals to formaldehyde vapor (of disinfectant strength) for 

 hours without causing their death. In Harrington's experi- 

 ments two rabbits were killed by formaldehyde in the disin- 

 fection of a room, and exhibited the following post mortem 

 appearances : Congestion and hemorrhage of the buccal 

 mucous membrane ; intense bronchitis with hyperaemia, and 

 consolidation of the lung with a purulent and slightly fibri- 

 nous exudate. There was also congestion of the abdominal 

 organs, including the liver, kidneys and spleen. As death 

 may occur, it is certainly unwise to attempt the disinfection 

 of premises with formaldehyde, when inhabited by men or 

 animals. The smaller insect pests and animal parasites are 

 sometimes killed by formaldehyde disinfection, but not in- 

 variably so. 



Formic aldehyde vapor is not injurious to plants, cloth- 

 ing, metals, or other like articles, as are sulphurous anhy- 

 dride or chlorine gas, and it bids fair to supersede all other 

 agents for the gaseous disinfection of premises infected with 

 pathogenic bacteria. Formalin may be diluted with § of its 

 bulk of water and evaporated by heat to generate formalde- 

 hyde gas, without any special apparatus. 



Harrington states that the evaporation of 110 Cc. of 



