Pure distilled water.  Sugar candy. ... . ... . ... . ... . ... . 200 grammes Bitartrate of potassium. ... . ... . 1.0 grammes Bitartrate of ammonia. ... . ... ... 0.5 grammes Sulphate of ammonia.,. ... . ... ... 1.5 grammes Ash of yeast. ... . ... . ... . ... . ... 1.5 grammes (1 gramme = 15.43 grains)

Let us boil the mixture, to destroy all germs of organisms that may exist in the air or liquid or on the sides of the flask, and then permit it to cool, after having placed, by way of extra precaution a small quantity of asbestos in the end of the fine curved tube.  Let us next introduce a trace of ferment into the liquid, through the other neck, which, as we have described, is terminated by a small piece of india-rubber tube closed with a glass stopper.

Here are the details of such an experiment:—­

On December 9th, 1873, we sowed some pure ferment—­saccharomyces pastorianus.  From December 11, that is, within so short a time as forty-eight hours after impregnation, we saw a multitude of extremely minute bubbles rising almost continuously from the bottom, indication that at this point the fermentation had commenced.  On the following days, several patches of froth appeared on the surface of the liquid.  We left the flask undisturbed in the oven, at a temperature of 25 degrees C. (77 degrees F.) On April 24, 1874, we tested some of the liquid, obtained by means of the straight tube, to see if it still contained any sugar.  We found that it contained less than two grammes, so that 198 grammes (4.2 oz.  Troy) had already disappeared.  Some time afterwards the fermentation came to an end; we carried on the experiment, nevertheless, until April 18, 1875.

There was no development of any organism absolutely foreign to the ferment, which was itself abundant, a circumstance that, added to the persistent vitality of the ferment, in spite of the unsuitableness of the medium for its nutrition, permitted the perfect completion of fermentation.  There was not the minutest quantity of sugar remaining.  The total weight of ferment, after washing and drying at 100 degrees C. (212 degrees F.), was 2.563 grammes (39.5 grains).

In experiments of this kind, in which the ferment has to be weighed, it is better not to use any yeast-ash that cannot be dissolved completely, so as to be capable of easy separation from the ferment formed.  Raulin’s liquid [Footnote:  M. Jules Raulin has published a well-known and remarkable work on the discovery of the mineral medium best adapted by its composition to the life of certain fungoid growth; he has given a formula for the composition of such a medium.  It is this that we call here “Raulin’s liquid” for abbreviation.