98 OUTLINES OF BACTEEIOLOGY 



sporing condition was destroyed by exposure for 24 hours to a moist 

 atmosphere containing only -0005 per cent, of chlorine. A further 

 example of its excellent germicidal qualities is given by De la Croix's 

 investigation, as a result of which it was shown that no development 

 of bacteria or moulds took place in an unboiled meat infusion when 

 chlorine, in the proportion of 1 : 15,600, was present in the atmosphere. 

 Miquel, however, puts the proportion much lower, viz. 1 : 4000. 



Mention has already been made of the germicidal properties of 

 various acids. We must now deal with the more important. 



Sulphuric Acid. Boer's experiments decided the proportion 

 necessary, both to restrain the development of bacteria and also 

 to destroy them when development had taken place. The time 

 of exposure for all these experiments was two hours. 



This acid is therefore a powerful germicide, but unfortunately 

 its use is limited to those substances which are to be disinfected 

 before being thrown away. It is not cheap, it inflicts nasty burns 

 on the skin and chars all organic substances. 



Nitric and Hydrochloric Acids are both excellent germicides in 

 themselves, but they are not cheap, and dangerous as well as 

 unpleasant to use. 



The following results obtained with hydrochloric acid, show the 

 proportions of acid to water, which are necessary to prevent 

 development of bacteria, and to destroy them outright. 



To RESTRAIN To DKSTROY 



DEVELOPMENT. VITALITY, 



Anthrax bacillus 1 : 3400 1 



Diphtheria bacillus- 1:3400 1 



Glanders bacillus 1 : 700 1 



Typhoid bacillus 1:2100 1 



1100 



700 



200 



300 



1350 



Cholera spirillum 1:5500 1 



Phosphoric Acid. A 0-3 per cent, solution of this acid will destroy 

 the typhoid bacillus in four or five hours. 



Lactic Acid. It is important to know exactly the germicidal 

 properties of this acid because of its extensive use in various 



