40 APPLIED BACTERIOLOGY FOR NURSES 



about 15 pounds are added to 1,000,000 gallons of water. 

 This is equivalent to approximately 0.5 part free chlorin 

 per 1,000,000 parts of water. (See also page 145.) 



Sulphur dioxid gas, produced by burning sulphur in 

 air, was formerly extensively used as a disinfectant for 

 sick rooms, but has now been largely discarded in favor 

 of formaldehyd. Ordinarily 4 pounds of sulphur are 

 burned for each 1000 cubic feet of air space, and the 

 room is kept sealed for at least eight hours. In order to 

 be efficacious the air in the room in which the sulphur 

 is burned should be moist. Sulphur fumigation is still 

 largely used to kill rats and vermin in combating the 

 spread of plague. 



Formaldehyd is a gaseous compound having an ex- 

 tremely irritating odor. It is most conveniently used 

 in the form of a watery solution containing about 40 

 per cent, of the gas, and known commercially as "for- 

 malin." A 2 per cent, watery solution of formalin 

 destroys the vegetative forms of bacteria within five 

 minutes. In the form of the gas formaldehyd is ex- 

 tensively used in the disinfection of sick rooms. At 

 least 4 ounces of formaldehyd should be allowed for 

 each 1000 cubic feet of air space. The details of such 

 disinfection are discussed on p. 163. 



lodin, in the form of tincture of iodin, is extensively 

 used as a disinfectant of the skin for surgical operations. 



Peroxid of hydrogen (H 2 2 ) is an energetic disin- 

 fectant. A 20 per cent, solution (a good commercial 

 hydrogen peroxid) will quickly destroy the pus-produc- 

 ing cocci and spore-free bacteria. It combines with 

 organic matter, becoming inert. It is prompt in its 

 action and not poisonous, but apt to deteriorate if not 



