CHEMICAL SCIENCE. 197 



animal charcoal, as a means of extracting these principles. He takes 

 the aqueous solution of the plant and boils it with bone-black, previ- 

 ously freed from phosphates by hydrochloric acid, until the liquor has 

 become colorless, and is no longer of a bitter taste ; the charcoal is 

 then washed with water, and, after drying, extracted with boiling- 

 alcohol. The latter extracts the bitter principle, or the organic base, 

 and it remains in a pure state after the evaporation of the alcohol. 

 Coloring matters may be previously separated from the juice by means 

 of a lead salt. Lebourdais states that he has in this w r ay obtained the 

 principles of digitalin, columbin, &c., in a crystallized state. An- 

 nales de Chimie et de Physique, XXIV. p. 58. 



ON THE PHENOMENA AND CAUSE OF FERMENTATION. 



AT the meeting of the American Association at New Haven, Mr. 

 Erni presented a paper on the phenomena and cause of fermentation, 

 of which the following is an abstract. It is well known among chem- 

 ists, that, notwithstanding the voluminous writings on fermentation, 

 we yet know very little of its original cause, and no one of the theo- 

 ries advanced is competent to the full explanation of the facts known 

 at present. It is doubtless true, that in this process, by the action of 

 the so-called ferment, organic bodies of complex composition, such as 

 sugar, etc., are decomposed into simpler substances. The cause of 

 these phenomena is considered by Liebig to be the power of the fer- 

 ment as a body in a state of decomposition, i. e. in chemical action, to 

 induce a similar transformation of compounds that come in contact 

 with it. Other chemists assume that fermentation is caused by the 

 development of fungi, and that different kinds of fermentation are due 

 to different fungi. The results which Mr. Erni has obtained, a part 

 of which have been fully corroborated by more recent examinations, 

 have enabled him to throw considerable light on some disputed points. 

 A great variety of experiments were published by Brendecke, accord- 

 ing to which porous substances, as straw, feathers, alum, pulverized 

 charcoal, potato-starch, flowers of sulphur, scraps of paper, and even 

 small fragments of some metals, as tin, for instance, induce fermenta- 

 tion in a solution of grape-sugar to which some tartrate of ammonia 

 had been added. After this it seemed probable that yeast, consisting 

 undoubtedly of vegetable ceils, might, like the substances mentioned, 

 produce fermentation in solutions of cane or grape sugar, not by means 

 of the vital force, but simply by its looseness and porosity. In re- 

 peating some of Brendecke 's experiments, Mr. Erni had used grape- 

 sugar prepared from honey by means of alcohol, and purified by boil- 

 ing with charcoal, and cane-sugar prepared from white refined sugar 

 re-crystallized from solution in hot water. In the experiments, one 

 part of sugar and eight of water were employed. First experiment. 

 Common straw r was treated with potash lye, to dissolve any gluten it 

 might contain. After twenty- four hours the straw was washed with 

 water, the last traces of potash removed by hydrochloric acid, and 

 finally the straw perfectly cleaned with %vater. The solution of 

 cane and grape sugar mixed with such straw underwent no change, 



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