EFFRONT'S HYDROFLUORIC ACID METHOD. 251 



stopped, by this quantity. The same authority has also showed 

 (IV.) that yeast can be gradually accustomed to large additions of 

 fluorine. In this manner a given yeast can be brought to with- 

 stand an addition of 300 m.grms. of HF per 100 c.c. without losing 

 its reproductive power. Doses below this limit up to about 200 

 m.grms. per 100 c.c. retard reproduction, but stimulate the decom- 

 posing energy of the organism, and therefore lead to a larger pro- 

 duction of alcohol. The yeast becomes so much accustomed to 

 this stimulant that it is subsequently rendered incapable of 

 unfolding its energies except when pitched in a mash also con- 

 taining fluorine, the yield of alcohol being otherwise far below 

 the normal standard. 



In practice the new hydrofluoric process is, in the main, carried 

 out as follows : For the preparation of the yeast-mash 4 parts per 

 cent, (by volume) are taken from the principal mash (previously 

 saccharified and cooled down to 30 C.), and a sufficient amount 

 of hydrofluoric acid (or fluoride) added, this being followed by 

 i volume of mother-yeast to each 4 volumes of mash taken. Of 

 course, at the commencement of the season a sufficiency of pure 

 culture yeast must be used instead. The amount of added acid is 

 regulated by the kind of yeast in use, i.e. by its susceptibility ; but 

 10 grams (say | oz.) of HF per hectolitre (22 galls.) of yeast-mash 

 will generally suffice. After the addition of the mother-yeast the 

 mash, which was pitched at 26 C., quickly warms up to about 

 31 C., at which temperature it is maintained. In this procedure 

 the older process described in the preceding paragraph is somewhat 

 modified : the heating of the saccharified yeast-mash up to 70 C., 

 which was there found advantageous, being, in the present instance, 

 abandoned (since the injurious organisms are suppressed by the 

 HF), as is also the separate addition of malt to the mash. In 

 addition to the properties already mentioned, hydrofluoric acid is 

 also credited with exercising a favourable influence on the diastatic 

 action, in that in presence of this acid a much smaller amount of 

 the said enzyme suffices to hydrolyse a given amount of starch in 

 a given time. The ratio of maltose and dextrin is also modified 

 in favour of the former, as much as 96 parts of maltose being 

 sometimes obtained per 100 parts of starch, whereas in presence 

 of HC1 (or H 2 S0 4 ) the highest percentage of maltose amounts to 

 75 (or 76) per cent., and in the absence of mineral acids to 74 per 

 cent. When the yeast-mash is matured (in about twenty hours' 

 time), one-fifth is set aside to serve as mother-yeast for the 

 succeeding mash. The residual four-fifths are incorporated with 

 the fresh, saccharified principal mash, previously mixed with enough 

 hydrofluoric acid (or ammonium fluoride) to make the (percentage) 

 content thereof equal to one-half that of the yeast-mash. This 

 proportion has been found to be sufficient ; and since high patent 

 royalties have to be paid to the " Socie'te' Gene" rale de Maltose 

 a Bruxelles," of which M. Effront is director for the use of 



