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tity present. We touch here upon the difficult problems 

 connected with the so-called co-ferments, and we are clearly 

 on the fringe of important discoveries. Indeed, many 

 facts are already at hand which only want of space com- 

 pels us to withhold for the purposes of the present article. 

 Some German chemists, Bredig among others, have been 

 able to imitate very closely certain fermentations by means 

 of finely-divided metals, such as platinum or gold, and 

 these curious ferment-like solutions may be " poisoned," 

 chloroformed, or killed just as if they were alive. This is 

 all extremely odd, and most perversely mechanical; but 

 there is something behind these phenomena which awaits 

 correlation with vinous fermentation. Meanwhile, about 

 three years ago the Zeitschrift filr Physikalische Chemie 

 published the following remarkable research, which must 

 furnish us with all the evidence we have leisure to adduce 

 on this occasion : In the course of his paper on the ' * Influ- 

 ence of Metals on the Hydrolysis of Cane Sugar, ' ' R. Von- 

 dracek draws attention to the fact that authorities differ 

 * ' as to the effect of metals on the well-known slow inversion 

 of saccharose by boiling water, ' ' and proves experimentally 

 that strips of platinum foil do not appreciably influence 

 the rate of inversion, thus confirming the results obtained 

 by Lindet. On the other hand saccharose (cane-sugar) is 

 rapidly inverted by boiling water in the presence of plati- 

 num black. Sugar solutions acquire a decidedly acid reac- 

 tion by heating with platinum black for fifteen minutes, 

 and the filtrates undergo inversion on further heating. If 

 after inverting a sugar solution by treatment with platinum 

 black for eight hours the powder be immediately heated 

 with a fresh solution, the latter developes no acidity, and 

 it is not inverted more rapidly than by water alone, but 

 the inverting property of the platinum black is restored by 

 exposure to air. Again, platinum black which has been 

 previously deoxidized by treatment with ammonia, has no 

 influence on the rate of inversion by pure water. From 

 these data it is concluded that the inversion by platinum 



