io8 



METHODS OF STERILISATION. 



solution in rainy weather, using pure rain-water for that purpose. 

 Like most of the salts of mercury, sublimate forms insoluble 

 compounds with albuminoids (e.g. in the blood), and has then no 

 longer any effect on bacteria. This reaction is prevented by 

 adding 5 grams of sodium chloride per litre of solution, since this 

 salt forms with the mercuric chloride a double salt soluble in 

 water. According to the researches of R. Koch, the spores of 

 Bacillus anthracis perish in an hour when immersed in this solu- 

 tion. For the prevention of their germination the presence of 

 i part of sublimate in 300,000 parts of water suffices. 



The earliest disinfectant employed was sulphurous acid, the 

 use of which for sulphuring wine casks has been handed down 

 from remote ages. In this process, so-called sulphur threads are 

 ignited and placed in the cask, being prevented from falling by 

 the bung. These sulphur threads are strips of linen about the 

 breadth of the finger, steeped in melted sulphur. The germicide 

 properties of gaseous sulphurous acid (sulphur dioxide) were 

 examined by G. .WOLFFHUGEL (I.); and G. LINOSSIER (I.) en- 

 deavoured to express in figures the relation between the percentage 

 content of a solution of this dioxide and the length of exposure 

 necessary to kill various germs. His experiments were not con- 

 ducted with bacteria, but with Eumycetes ; they are, nevertheless, 

 given in the following table : 



With regard to the deadening of wine-must by sulphurous 

 acid, referred to in n, mention may be made of the discovery of 

 this observer that 25 c.c. of S0 2 per litre sufficed not only to 

 hinder the inception of fermentation in wine-must, but also to 

 bring it to a standstill when already in progress. The presence of 

 a small quantity by itself inert of another mineral acid was 

 found to increase the power of the sulphurous acid in a remarkable 

 degree. The subsequent fate of this latter in sulphured wine 

 varies : a small portion combines with the aldehydes, a little (often 

 merely a trace) of which is always present, to form aldehyde- 

 sulphurous acid, a compound of agreeable odour, but the bulk is 

 converted into sulphuric acid and is then found as potassium 

 sulphate. Several experiments in this connection have been con- 



