FOEMALDEHYDE 339 



tratiBg power of formaldehyde is nil in the case of moist 

 substances, and that sterilization is not always complete 

 when micro-organisms are imbedded in, or covered by, dry 

 pervious material. Still, formaldehyde is the best practical 

 disinfectant now known for the sterilization of infected 

 premises.* The gas is most effective between 60 degrees 

 and 70 degrees F. It should not be used if air tem- 

 perature is below 50 degrees F. It is not so operative 

 in damp air, and the premises should be closed tight from the 

 outer air, in order that the disinfection may be thorough. 

 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 ex- 

 perimenters have subjected animals to formaldehyde vapor 

 (of disinfectant strength) for hours without causing their 

 death. In Harrington's experiments two rabbits were killed 

 by formaldehyde in the disinfection of a room, and exhibited 

 the following post-mortem appearances: Congestion and 

 hemorrhage of the buccal mucous membrane ; intense bron- 

 chitis with hyperasmia, and consolidation of the lung with a 

 purulent and slightly fibrinous exudate. There was also 

 congestion of the, abdominal organs, including the liver, kid- 

 neys and spleen. As death may occur, it is certainly unwise 

 to attempt the disinfection of preipises . with formaldehyde, 

 when inhabited by men or animals. The smaller insect pests 

 and -animal parasites are sometimes killed by formaldehyde 

 disinfection, but not invariably so. 



Internal Action. — Solutions of formaldehyde are in- 

 tensely irritant. ISTausea, vomiting, coma with slow pulse, 

 and death have followed its ingestion. The red blood cells 

 are altered in form, and destructive changes have been noted 

 in the liver and kidneys. Formaldehyde escapes unchanged 

 in the urine. 



Formic aldehyde vapor is not injurious to clothing, 

 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 



* It does not kill rats, but burning sulptiur is effective for this purpose. 



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