MICROSCOPICAL AND PHYSIOLOGICAL EXAMINATION. 17 



in many breweries are never sufficiently cleansed should be 

 disinfected by treatment with a solution of chloride of lime. 

 Will, who experimented with material obtained from a brewery, 

 recommends a solution containing 1 per cent, of active 

 chlorine (corresponding to about 3 3^ kg. of good commercial 

 chloride of lime to 100 liters of water). The filter-bags must 

 be washed with pure water after this treatment In physio- 

 logical laboratories, where it is of especial importance to guard 

 against any invasion of foreign germs, an alcoholic solution of 

 salicylic acid will prove of service (it is often used by Hansen 



FIG. 3. 



Pasteur's Flask. 



in the Carlsberg laboratory for cleansing tables). The action 

 of this substance, even in a diluted state, in checking fer- 

 mentation is generally known. 1 Eecently, hydrofluoric acid 

 has also been employed as a disinfectant (see p. 25). 



5. FLASKS : PASTEUR, CHAMBERLAND, FREUDENREICH, 

 HANSEN, AND CARLSBERG FLASKS. 



All vessels in which cultures are made must satisfy the 



1 Biernacki and others have proved that substances otherwise 

 possessed of antiseptic power can, when very much diluted, act as 

 stimulants on yeast-fungi. Thus, alcoholic fermentation is promoted by 

 the addition of corrosive sublimate in a dilution of 1 in 300,000, by 

 salicjlic acid solution of the strength 1 in 6000, and by boracic acid 

 solution of the strength 1 in 8000. 



c 



