18 MICRO-ORGANISMS AND FERMENTATION. 



used, in which the formaldehyde is produced by combus- 

 tion of methyl-alcohol. Formaline is also used, in a solution of 

 1-2 per cent., for washing utensils, etc. 



According to WINDISCH yeast-cells are less sensible to the 

 action of formaldehyde than bacteria. 



Very favourable results have also been obtained of late years 

 by means of antinonnine, a creosote combination mixed with soap 

 and other substances. It is, for instance, a powerful remedy for 

 dry-rot, and may, according to the results of AUBRY, be used 

 profitably in the fermentation industries for cleansing walls and 

 utensils which do not come into contact with the liquids to be 

 fermented. 



In the manufacture of spirit and pressed yeast, researches 

 have been carried on for some years past as to the effect of anti- 

 septics on the yeast-cell, its power of fermentation, production 

 of alcohol, and multiplying. Thus, HAYDUCK (1881) found that 

 very slight quantities of sulphuric and lactic acids are capable 

 of furthering both the fermentation and the growth of the 

 yeast. In 1882 HEINZELMANN found that traces of salicylic 

 acid increase the fermentative power, the yeast forming a 

 larger amount of alcohol than otherwise within a given time. 

 Later, BIERNACKI (1887) and SCHULZ (1888) found that all 

 antiseptics under certain conditions, especially in minute doses, 

 possess the property of accelerating and increasing alcoholic fer- 

 mentation. Of similar import are the recent statements of 

 EFFRONT, that it is possible to stimulate the yeast-cell by using 

 small quantities of hydrofluoric acid. According to EFFRONT, 

 the addition of 0'3 grammes of ammonium fluoride to 100 c.c. 

 entirely prevents the propagation of the yeast-cells, but does 

 not destroy the fermentative power. It is possible, he says, by 

 successive treatment, beginning with very small doses, to 

 accustom the yeast to larger quantities of this poison, the 

 amount varying with the selected species. First, the fermenta- 

 tion is introduced in 100 c.c. of wort with 20 mgr. of hydro- 

 fluoric acid ; when half the sugar has been fermented, 100 c.c. 

 of the fermenting liquid are mixed with 900 c.c. of wort contain- 

 ing 40 mgr. of hydrofluoric acid per 100 c.c. This procedure is 

 continued till the last yeast is made to ferment in the presence 

 of 300 mgr. of hydrofluoric acid per 100 c.c. of wort. In a 



