30 Proceedings of the First Convention 



same subject, and stated that for the destruction of mosquitoes, 

 10 grammes of cyanide to the cubic metre should be used, the 

 exposure lasting six hours. His plan for large rooms, like hospi- 

 tal wards, was as follows, which he stated would obviate the 

 danger from violent ebullition, as occurs when large pieces of 

 the salt are dropped in the acid, and will also give plenty of 

 time for the operator to leave the room. 



"The process consists in placing the salt with a little 

 water in a porcelain cask of sufficient capacity, and the 

 sulphuric acid conveniently diluted in another cask which 

 has a faucet. Place a porcelain or enameled iron vessel in the 

 mouth of the first cask, holding it in place by wires, giving it 

 a slight inclination, so that the liquid poured into it will run into 

 the interior of the cask ; place the cask containing the sulphuric 

 acid upon the table so that the faucet will be in the air ; place 

 the second cask upon the floor so that the vessel attached to 

 its mouth will be just beneath the faucet. Having prepared 

 everything in this way, and the time comes to verify the re- 

 action, calmly turn the faucet so that the solution of sulphuric 

 acid will fall on the small vessel and run into the cask con- 

 taining the cyanide. It is easily understood that by using this 

 artifice there will be plenty of time to escape from the action of 

 the gas and to complete the operation with calmness and 

 surety." 



Other plans for ridding a house may be used, such as the 

 burning of bubac, or Persian powder, etc., or roll sulphur, but 

 the latter would require the removal of fabrics, etc. 



For a full and interesting account of the use of this acid, 

 in the destruction of household insects, with a description of 

 its practical application, I refer you to Dr. Howard's article 

 published in the Government Public Health Reports, November 

 13. 1903, pages 1977 to 1982. 



Dr. Preston H. Bailhache added the following remarks : 

 Of course, this hydrocyanic acid gas is a very dangerous gas 

 to be used, and would probably never be necessary except in 

 a very thoroughly infected house. But for railroad cars it 

 seems to me it would be ideal ; where they infect railroad cars 

 it can be emptied and the gas put in. In this case I think the 

 operation would be perfect. 



