204 MANUAL OF BACTERIOLOGY. 



tion. The candle is placed in a suitable fire-proof dish, 

 it is then ignited, and generation of the gas is allowed to 

 proceed in the tightly closed room. 



Sulphur Dioxide. This substance is used extensively 

 for house disinfection, and is usually prepared by burning 

 sulphur. Much difference of opinion exists regarding the 

 value of it as a disinfectant. The spores of anthrax are 

 not killed by several days' exposure to the liquefied gas. 

 Anthrax and other bacilli are destroyed in thirty minutes 

 when exposed on moist threads in an atmosphere contain- 

 ing one volume per centum of the gas. An exposure of 

 twenty-four hours in an atmosphere containing four vol- 

 umes per centum of the gas will destroy the organisms of 

 typhoid fever, diphtheria, cholera and tuberculosis. The 

 presence of moisture greatly enhances the activity of the 

 disinfectant, owing to the formation of the more energetic 

 sulphurous acid. 



For the destruction of insects, such as mosquitoes, this 

 agent is superior to formaldehyde. Its application for this 

 purpose is important in preventing the spread of yellow 

 fever and malaria. 



In practice, at least 3 pounds of sulphur per 1000 cubic 

 feet should be used, and moisture must be present. This 

 latter requirement can be fulfilled by evaporating several 

 quarts of water within the tightly closed room just prior to 

 generating the gas. In using powdered or flowers of sul- 

 phur, the necessary amount is placed on a bed of sand or 

 ashes in an iron pot, which should rest on a couple of 

 bricks in a pan or other vessel containing an inch or two 

 of water. The sulphur is ignited by means of some glow- 

 ing coals, or by moistening with alcohol and applying a 

 a match. Difficulty is often experienced in keeping the sul- 

 phur burning, and for this reason it is surer and more con- 

 venient to use the so-called sulphur candles now on the 



