greatest possible quantity to have been absorbed, that was required by the yeast formed in the fermentation of 150 grammes (4.8 Troy ounces) of sugar.  We shall better understand the significance of this result later on.  Let us repeat the foregoing experiment, but under altered conditions.  Let us fill, as before, our flask with sweetened yeast-water, but let this first be boiled, so as to expel all the air it contains.  To effect this we arrange our apparatus as represented in the accompanying sketch. (Fig 2.) We place our flask, A, on a tripod above a gas flame, and in place of the vessel of mercury substitute a porcelain dish, under which we can put a gas flame, and Which contains some fermentable, saccharine liquid, similar to that with which the flask is filled.  We boil the liquid in the flask and that in the basin simultaneously, and then let them cool down together, so that as the liquid in the flask cools some of the liquid is sucked from the basin into the flask.  From a trial experiment which we conducted, determining the quantity of oxygen that remained in solution in the liquid after cooling, according to M. Schutzenberger’s valuable method, by means of hydrosulphite of soda [Footnote:  NaHSO2, now called sodium hyposulphite.—­D.C.R.], we found that the three litres in the flask, treated as we have described, contained less than one milligramme (0.015 grain) of oxygen.  At the same time we conducted another experiment, by way of comparison (Fig. 3).  We took a flask, B, of larger capacity than the former one, which we filled about half with the same volume as before of a saccharine liquid of identically the same composition.  This liquid had been previously freed from alterative germs by boiling.  In the funnel surmounting A, we put a few cubic centimetres of saccharine liquid in a state of fermentation, and when this small quantity of liquid was in full fermentation, and the yeast in it was young and vigorous, we opened the tap, closing it again immediately, so that a little of the liquid and yeast still remained in the funnel.  By this means we caused the liquid in A to ferment.  We also impregnated the liquid in B with some yeast taken from the funnel of A. We then replaced the porcelain dish in which the curved escape tube of A had been plunged, by a vessel filled with mercury.  The following is a description of two of these comparative fermentations and the results they gave.

[Illustration with caption:  Fig 2]

[Illustration with caption:  Fig. 3]

The fermentable liquid was composed of yeast-water sweetened with 5 per cent, of sugar—­candy; the ferment employed was sacchormyces pastorianus.

The impregnation took place on January 20th.  The flasks were placed in an oven at 25 degrees (77 degrees F.).

Flask A, without air.

January 21st.—­Fermentation commenced; a little frothy liquid issued from the escape tube and covered the mercury.