CHE5IICAL SCIENCE. 229 



experiments suggest different views, and afford a certainty that in the cases 

 specified the phenomena are essentially the same, and that in both the yeast 

 globules multiply; but that, in the first case, when the fermentation is con- 

 cluded, all the globules, young and old, are deprived of their soluble 

 nitrogcnized matter, and that what they possessed of nitrogenous aliment 

 has become insoluble and fixed in the fresh globules that have been formed. 

 Yeast in this state has no action upon pure sugar. In the case of fermenta- 

 tion in the presence of albuminoid matters, many globules become exhausted, 

 but most of the new ones leave the liquid filled with nitrogenous and mineral 

 matter, and able to live upon them in a fresh solution of sugar. 



M. Pasteur also notes the fact, that succinic acid and glycerine are products 

 of fermentation: and the formation of the former substance appears to exer- 

 cise an important influence on the flavor of alcoholic drinks, although the 

 quantity is small. Good Bordeaux contains 7.412 grains of glycerine in a 

 litre, and 1.48 grains of succinic acid. M. Pasteur remarks, "The flavor of 

 this acid is peculiar, and when it is mixed with water, alcohol, and glycerine, 

 in the proportions obtained by fermentation, one is surprised to observe the 

 extent to which the mixture resembles wine." 



The conclusion of M. Pasteur's paper expresses a conviction that a just 

 consideration of the facts he adduces will show that alcoholic fermentation 

 is an act correlative with the life and the organization of the yeast globules, 

 and not with their death or putrefaction. 



Professor Van den Broek, of Utrecht, also publishes the following conclu- 

 sions he has arrived at, respecting processes of fermentation and putre- 

 faction : 



1. Fresh juice of the grape, which has never been in contact .with the 

 atmosphere, and has been kept absolutely free from it, suffers no change in, 

 a temperature of 20 to 28 C. (80 to 83 F.) after months or even years. 



2. The fermentation of grape-juice depends upon the vegetation of the 

 yeast cellules, and is, therefore, absolutely dependent upon their development 

 and growth. 



3. It has, as yet, not been conclusively demonstrated whether any yeast 

 globules or their germ are present in the juice of ripe and perfect grapes. 



4. The impulse necessary for the development of the cellules and for the 

 commencement of fermentation is not given by the oxygen, but by one or 

 more agents contained in the air, which may be destroyed by heat, or 

 retained by filtering it through cotton. These agents may be wanting in a 

 limited volume of atmospheric air, a case not at all rare. In this point 

 fermentation is allied to other species of vegetation, such as mould, the 

 formation of which is dependent upon the very same conditions. 



5. Fermentation in fresh grape-juice is induced by the introduction of 

 yeast only and alone, which must not be too old; no atmospheric agents are 

 required, and the yeast itself need never to have been in contact with the 

 atmosphere. 



6. Fresh grape-juice, after being exposed for some minutes to the tem- 

 perature of boiling water, frequently ceases to ferment in contact with 

 atmospheric air. 



7. Oxygen, although it does not induce fermentation, acts decomposingly 

 upon the fresh as well as the boiled juice, by being absorbed and forming 

 carbonic acid; the fresh juice, and the parenchyma of the grapes suspended 

 in it, assume under its influence, in a short time, a brown tint, which turns 

 gradually darker. 



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