288 STUDIES ox FERMENTATION. 



during the first few days did the absorption by the concentrated 

 potash leave a very minute residue. By April 2Gth all libera- 

 tion of gas had ceased, the last bubbles having risen in the 

 course of April 23rd. The flask had been all the time in the 

 oven, at a temperature between 25° C. and 28° C. (77° F. and 

 83° F.). The total volume of gas collected was 2-135 litres 

 (130"2 cubic inches). To obtain the whole volume of gas 

 formed we had to add to this what was held in the liquid in the 

 state of acid carbonate of lime. To determine this we poured a 

 portion of the liquid from the flask into another flask of similar 

 shape, but smaller, up to a gauge-mark on the neck.* This 

 smaller flask had been previously filled with carbonic acid. 

 The carbonic acid of the fermented liquid was then expelled b}^ 

 means of heat, and collected over mercury. In this way we 

 found a volume of 8'322 litres (508 cubic inches) of gas in 

 solution, which, added to 2'135 litres, gave a total of 10 457 

 litres (638 '2 cubic inches) at 20° and 760, which calculated to 

 0° C. and 760 mm. atmospheric pressure (32° F. and 30 inches) 

 gave a weight of 19'70 grammes (302'2 grains) of carbonic acid. 

 Exactly half of the lime of the tartrate employed got used 

 up in the soluble salts formed during fermentation ; the other 

 half was partly precipitated in the form of carbonate of lime, 

 partly dissolved in the liquid by the carbonic acid. The soluble 

 salts seemed to us to be a mixture or combination of 1 equiva- 

 lent of metacetate of lime, with 2 equivalents of the acetate, 

 for every 10 equivalents of carbonic acid produced, the whole 

 corresponding to the fermentation of 3 equivalents of neutral 

 tartrate of lime.f This point, however, is worthy of being 



* We had to avoid tilling the small flask completely, for fear of causing 

 some of the liquid to pass on to the surface of the mercury in the 

 measuring tube. The lii^uid condensed bj- boiling forms pure water, the 

 solvent affinity of which for carbonic acid, at the temperature we employ, 

 is well known. 



f The following is a curious consequence of these numbers and of the 

 nature of the products of this fermentation. The carbonic acid liberated 

 being quite pure, especiallj' when the liquid has been boiled to expel all 

 air from the flask, and capable of perfect solution, it follows that, the 



