In order to expel all the air dissolved in the water and adhering to the solid substances, we first placed our flask in a bath of chloride of calcium, in a large cylindrical white iron pot, set over a flame. The exit-tube of the flask was plunged in a test-tube of Bohemian glass three-quarters full of distilled water, and also heated by a flame. We boiled the liquids in the flask and test-tube for a sufficient time to expel all the air contained in them. We then withdrew the heat from under the test-tube, and immediately afterwards covered the water which it contained with a layer of oil, and then permitted the whole apparatus to cool down. [Illustration: Fig. 67.] Next day we applied a finger to the open extremity of the exit-tube, which we then plunged in a vessel of mercury. In this particular experiment which we are describing, we permitted the flask to remain in this state for a fortnight. It might have remained for a century without ever manifesting the least sign of fermentation, the fermentation of the tartrate being a consequence of life, and life after the boiling no longer existed in the flask. When it was evident that the contents of the flask were perfectly inert, we impregnated them rapidly, as follows:—All the liquid contained in the exit-tube was removed by means of a fine caoutchouc tube, and replaced by about 1 c.c. (about 17 minims) of liquid and deposit from another flask, similar to the one we have described, but which had been fermenting spontaneously for twelve days; we lost no time in refilling completely the exit-tube with water which had been first boiled and then cooled down in carbonic acid gas. This operation lasted only a few minutes. The exit-tube was again plunged under mercury. Subsequently the tube was not moved from under the mercury, and as it formed part of the flask, and there was neither cork nor india-rubber, any introduction of air was consequently impossible. The small quantity of air introduced during the impregnation was insignificant, and it might even be shown that it injured rather than assisted the growth of the organisms, inasmuch as these consisted of adult individuals which had lived without air and might be liable to be damaged or even destroyed by it. Be this as it may, in a subsequent experiment we shall find the possibility removed of any aeration taking place in this way, however infinitesimal, so that no doubt may linger on this subject.