Page:Popular Science Monthly Volume 1.djvu/596

580 and that it is by carrying off a portion of oxygen from the last that the ferment causes the fermentation to commence the equilibrium between the principles of the sugar being disturbed, they combine afresh to form carbonic acid and alcohol."

The three views here before us may be familiarly exemplified by supposing the sugar to be a card-house. According to Stahl, the ferment is somebody who knocks the table, and shakes the card-house down; according to Fabroni, the ferment takes out some cards, but puts others in their places; according to Thenard, the ferment simply takes a card out of the bottom story, the result of. which is that all the others fall.

As chemistry advanced, facts came to light which put a new face upon Stahl's hypothesis, and gave it a safer foundation than it previously possessed. The general nature of these phenomena may be thus stated: A body, A, without giving to or taking from another body, B, any material particles, causes B to decompose into other substances, C, D, E, the sum of the weights of which is equal to the weight of B, which decomposes.

Thus, bitter almonds contain two substances, amygdaline and synaptase, which can be extracted in a separate state, from the bitter almonds. The amygdaline thus obtained, if dissolved in water, undergoes no change; but, if a little synaptase is added to the solution, the amygdaline splits up into bitter-almond oil, prussic acid, and a kind of sugar.

A short time after Cagniard de la Tour discovered the yeast-plant, Liebig, struck with the similarity between this and other such processes and the fermentation of sugar, put forward the hypothesis that yeast contains a substance which acts upon sugar, as synaptase acts upon amygdaline; and as the synaptase is certainly neither organized nor alive, but a mere chemical substance, Liebig treated Cagniard de la Tour's discovery with no small contempt, and, from that time to the present, has steadily repudiated the notion that the decomposition of the sugar is in any sense the result of the vital activity of the Torula. But, though the notion that the Torula is a creature which eats sugar and excretes carbonic acid and alcohol, which is not unjustly ridiculed in the most surprising paper that ever made its appearance in a grave scientific journal, may be untenable, the fact that the Torulæ are alive,