77 6 TEE POPULAR SCIENCE MONTELY. 



expose them to great heat, our task would be accomplished. Such 

 isolation is of course impossible, but we make use of heat in the de- 

 struction of germs which have found a resting-place in clothes and 

 bedding. The articles are placed in ovens or hot-air chambers, the 

 temperature of which can be raised many degrees above the boiling- 

 point of water. A high temperature, however, has less effect upon 

 the spores than upon the mature organisms, but successive heatings 

 are found to effect the desired result. During their development the 

 spores rapidly pass through several stages, in which they become 

 softened and far more amenable to the action of heat. Exposure to a 

 current of steam at a temperature of 212° is a still more satisfactory 

 method than the use of dry heat. It involves less injury to the articles 

 to be disinfected (a very important point when blankets and other 

 woolen goods have to be dealt with), and it is more simple, more 

 rapid, and more certain in its action. When the necessary appliances 

 are not available, washing the clothes with soap and hot water, and 

 then boiling them for several hours, form an effective substitute. Ex- 

 posure to sun and air will serve to complete the purification. 



For the disinfection of the air of rooms many substances are rec- 

 ommended and employed, but the way in which they are generally 

 used causes them to act merely as deodorants. Even at the present 

 day, the fact is very incompletely realized that ventilation — that is, 

 the continual admission of fresh air — is the only safe method of purify- 

 ing the atmosphere of rooms containing sources of infection. It is 

 simply useless to place saucers containing chloride of lime, carbolic 

 acid, or Condy's fluid in a contaminated atmosphere with the hope 

 that the germs floating about therein will be caught and killed, like 

 mice in a trap. The chlorine, doubtless, will remove some offensive 

 odors and readily diffuse itself throughout a room, but to act as a true 

 disinfectant it must be so much concentrated that the air in the space 

 containing it would be quite irrespirable by human beings. It is, 

 however, when used scientifically, the best disinfectant we possess for 

 purifying the walls, etc., of an empty room. All the openings should 

 be rendered as nearly air-tight as possible, and the evaporation of a 

 large quantity of water in the room aids the action of the chlorine. 

 It is easily generated by adding hydrochloric acid to bleaching-powder. 

 For deodorizing purposes in sick-rooms and passages, a gas called 

 "euchlorine" will be found very serviceable. It is produced when a 

 few crystals of chlorate of potassium are dropped into a little hydro- 

 chloric acid. The mixture can be conveniently made in a small wide- 

 mouthed bottle, which should be placed as near the ceiling as possible, 

 so that the gas may descend into the room. Chlorine and its com- 

 pounds are much heavier than atmospheric air. Bromide is even more 

 powerful as a disinfectant than chlorine, and both are far superior to 

 sulphurous acid. 



Carbolic acid has been much overrated as a disinfectant. The 



