94 



OUTLINES OF BACTEKIOLOGY 



1000 cubic feet of space. From what has just been stated, it is obvious 

 that the walls, floors, etc., must be sprayed with water preparatory 

 to being subjected to the action of the fumes. The room should 

 be kept closed for at least 24 hours. The employment of sulphur 

 fumes, under pressure, is probably the most convenient method for 

 the disinfection of ships. 



In the fermentation industries this method of disinfection is very 

 extensively used. The following table shows how far sulphur dioxide 

 in solution is effective in the destruction of yeasts and other fungi : 



According to Linossier, 25 c.c. of sulphur dioxide per litre is 

 sufficient, not only to prevent fermentation from making a start, but 

 also to stop it when it has started. The use of sulphur dioxide in the 

 gaseous form is not often resorted to in the fermentation industries, 

 because it attacks the metal iittings, and irritates the lungs of the 

 workmen. In breweries the use of calcium bisulphite (Ca (11803)2) ^^ 

 disinfecting the fermenting tuns is very extensive. 



Milk of Lime or Calcium Hydroxide is often employed to wash the 

 walls of malt-houses, etc. It is fairly good when fresh, but, when it has 

 stood for some time, it becomes converted into the carbonate which has 

 no injurious effect on micro-organisms. The reaction which takes 

 place is as follows : 



Ca (0H)2 + CO2 = CaCOg + H^O. 



calcium 

 hydrate 



calcium 

 carbonate 



According to one observer, the typhoid bacillus and the cholera- 

 spirillum in broth cultures are killed in four or five hours by the 

 addition of O'l per cent, of calcium oxide. Again, the dejections of 

 typhoid patients can be sterilised in six hours by the addition of 

 3 per cent, of this substance, and, when the percentage is raised to 6, 

 in two hours. The practical value of the application of lime-wash to 



