FOURTH PART 

 WINES AND [VINEGARS 



INDUSTRIAL METHODS IN THE MANUFACTURE OF 



VINEGAR 



The theory of Liebig in regard to fermentations, 

 which Pasteur had combatted, was applied also to a 

 category of phenomena to which Liebig had given the 

 name Eremacausis, or dry rot, and which were especially 

 phenomena of oxidation in contact with the air. The 

 type to which he referred them by preference was the 

 oxidation of alcohol by platinum black, discovered by 

 Dobereiner. When drops of concentrated alcohol are 

 allowed to fall on finely divided platinum, the mass be- 

 comes hot and gives off vapors which have both the 

 suffocating odor of aldehyde, and the penetrating and 

 pungent odor of vinegar. The explanation of the phe- 

 nomenon is very simple. The alcohol is burned at the 

 expense of oxygen which the platinum holds condensed 

 in its pores. A partial oxidation gives aldehyde; a more 

 complete one, acetic acid; an oxidation still more com- 

 plete would give carbonic acid, as when alcohol burns 

 with a flame in contact with air. As for the platinum, 

 it remains unaltered. 



Such was the type, purely chemical, to which Liebig 

 referred the oxidizing action of the soil on the organic 

 substances which it contains, nitrification, the dry rot 

 of wood, the oxidation of the siccative oils, and, by ex- 



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