STUDIES ON FERMENTATlOTSr. 297 



begun to manifest itself. On the 24tli this fermentation was 

 proceeding with astonishing rapidity, which continued during 

 the 25th and 26th. During the evening of the 26th it 

 slackened, and on the 27th all signs of fermentation had ceased. 

 This was not, as might be supposed, a sudden stoppage, due 

 to some unknown cause ; the fermentation was actually com- 

 pleted, for when we examined the fermented liquid on the 28th 

 we could not find the smallest quantity of lactate of lime. If 

 the needs of industry should ever require the production of 

 large quantities of butyric acid, there would, beyond doubt, be 

 found in the preceding fact valuable information in devising an 

 easy method of preparing that product in abundance.* 



Before we go any further, let us devote some attention to 

 the vibrios of the preceding fermentations. 



On May 27th, 1862, we completely filled a flask, capable 

 of holding 2'780 litres (about five pints), with the solution of 

 lactate and phosphates. f We refrained from impregnating it 

 with any germs. The liquid became turbid from a develop- 



* In what way are we to account for so great a difference between the 

 two fermentations that we have just described ? Probablj', it was owing 

 to some modification eflfected in the medium by the previous life of the 

 bacteria, or to the special character of the vibrios used in impregnation. 

 Or, again, it might have been due to the action of the air, which, under 

 the conditions of our second experiment, was not absolutely eliminated, 

 since we took no precaution against its introduction at the moment of 

 filling our flask, and this would tend to facihtate the multiplication of 

 anaerobian vibrios, just as, under similar conditions, would have been 

 the case if we had been dealing with a fermentation by ordinary yeast. 



t In this case the liquid was composed as follows : — a saturated solu- 

 tion of lactate of lime, at a temperature of 25° C. (77" F.) was prepared, 

 containing for every 100 c.c. (3| fl. oz.) 25-6o grammes (394 grains) of the 

 lactate, CgH^O^GaO [new notation, CgHioCaOg]. This solution was 

 rendered very clear by the addition of one gramme of phosphate of 

 ammonia and subsequent filtration. For a volume of 8 litres (14 pints) 

 of this clear, saturated solution, we used [1 gramme = 15 '43 grains] : — 

 Phosphate of ammonia . . . . . . . . 2 grammes. 



Phosphate of potassium .. .. .. ..1 ,, 



Phosphate of magnesium . . . . . . . . 1 , , 



Sulphate of ammonia . . . . . . . . . . 0"5 ,, 



