SULPHUR DIOXIDE 53 



70 per cent, alcohol. Practical surgical work seems to indi- 

 cate that for skin disinfection before operation all bacteria 

 are destroyed in the epidermis. Some defenders of this 

 method maintain that its penetrating powers exceed any 

 other known practical disinfectant. The method, while 

 undoubtedly excellent, must remain for a while sub judice 

 before one can accept this statement. Chloroform kills 

 vegetative bacteria and restrains spores, even in small 

 quantities. Ordinary soap is a good disinfectant, particularly 

 by its solvent power on the simple organic substances. Its 

 effect is increased by the addition of common washing 

 soda. 



Acids. The strong mineral acids are not practical disin- 

 fectants, but nevertheless are very efficient. Boric acid kills 

 the less resistant organisms in a 2 per cent, solution, but only 

 after some hours' exposure. 



Gaseous Disinfectants. There are only three of practical 

 value. They are sulphur dioxide, oxygen from hydrogen 

 dioxide, and formaldehyde. Chlorin is not included here 

 because it is seldom used in its pure state, since it is highly 

 poisonous and destructive; it is, however, eminently effi- 

 cient. (See p. 51.) 



Sulphur Dioxide. Sulphur dioxide is used for hospitals, 

 apartments, and ships, and is especially well suited to the 

 destruction of rats and insects. It is more efficient when there 

 is considerable moisture in the air. When conditions are 

 suitable for disinfection, anthrax bacilli in the vegetative 

 condition are destroyed in thirty minutes when there is 1 

 volume per cent, of the gas in the given space. " Four pounds 

 of sulphur burned for each 1000 cubic feet will give an excess 

 of gas." Some water should be sprayed in the room or an 

 open vessel containing water should be there. It has been 

 suggested that the sulphur candles of commerce be burned, 

 resting on a brick in a bucket of water. The gas, while very 

 efficient, cannot be used as a general disinfectant because of 

 its destructive action upon colors, fabrics, and metals. 



