EFFRONTS HYDROFLUORIC ACID METHOD. 249 



the organism is allied to, or identical with, the above-mentioned 

 bacillus. The method described by E. DELACROIX (I.) utilises, by 

 a similar course of treatment, the sweet whey formed as a waste 

 product in dairies. 



150. Effront's Hydrofluoric Acid Method. 



It is found impracticable to protect the fermentation of dis- 

 tillery mash from injurious bye-fermentations by sterilising the 

 mash before adding the pitching yeast, since such treatment would 

 also kill the diastase, the continuance of whose saccharifying action 

 during the fermentation cannot be dispensed with. Moreover, 

 such sterilising would not be of much value, since it is practically 

 impossible to protect such large quantities of fermentable material 

 from subsequent infection by extraneous germs during the fer- 

 mentation. The only course, therefore, is to devise some means 

 of restricting the development of the invading organisms. The 

 souring of the yeast-mash is, as already explained, a method of 

 this kind. This method, however, was not based upon a recogni- 

 tion of the true nature of the evil to be overcome, but is rather 

 the result of multifarious experiments which finally demonstrated 

 that a strongly acidified yeast-mash affords a guarantee for' the 

 satisfactory progress of fermentation in the mash proper, and pro- 

 tection from injurious bye-fermentations. Consequently, as soon 

 as the anti-bacterial action of lactic acid was recognised as the 

 actual agency at work in this process, investigation into the suit- 

 ability of other bacterium poisons for the purpose in question 

 followed as a matter of course. Thus in 1886, U. GAYON and 

 G. DUPETIT (I.) ascertained that an addition -of o. i gram of basic 

 nitrate of bismuth per litre of mash was able to keep the fermen- 

 tation free from contamination. Many other investigators have 

 occupied themselves with the same subject, from which it is 

 evident that the task is by no means an easy one. As a matter 

 of fact, the antiseptic sought must, to be suitable, unite in itself 

 several properties. For one thing, it must be able to restrict the 

 development of the Schizomycetes without injuring the yeast 

 present at the same time. Furthermore, it must not impart any 

 evil odour or flavour to the alcohol produced, and must, therefore, 

 be non-volatile and remain behind in the distillation residue 

 (grains) without being in its actual condition of dilution dan- 

 gerous to the animals subsequently fed thereon. Finally, the 

 employment of the bacterium poison should not entail any great 

 expense. It is, however, difficult to find a substance capable of 

 fulfilling the whole of these conditions. The metallic poisons, 

 such as the aforesaid bismuth salt, must be at once dismissed from 

 consideration. The acid sulphite of lime (calcium bi-sulphite), 

 which has been frequently recommended, is rendered unsatis- 

 factory owing to the partial reduction of its sulphurous acid, by 





