b. Fluid in contact with Ordinary Air and its Particles; Neck of Flask Sealed after the Fluid had become Cold.
No. IV.—Urine remained quite bright and clear during the fifteen days in which it was kept under observation in the water-bath.[48]
No. V.—Hay Infusion after forty-four hours showed a well-marked turbidity. In sixty-eight hours there was an increase in the amount of turbidity, and also some sediment. During the next forty-eight hours turbidity and sediment gradually increased, whilst the colour of the fluid (originally that of port wine) became several shades lighter. Except that it grew still lighter in colour, and that the amount of sediment increased, it underwent no further obvious change during the fifteen days in which it remained in the bath.[48]
No. VI.—Turnip Infusion underwent no change during the fifteen days in which it was kept in the bath under observation.[48]
c. Fluid in a Flask with a Neck two feet long, and having Eight acute Flexures.
No. VII.—Urine remained quite bright and clear during the fifteen days in which it was kept under observation in the water-bath.[48]
No. VIII.—Hay Infusion remained bright and clear for twelve days. On the thirteenth day a very slight (almost inappreciable) sediment was seen, which scarcely underwent any obvious increase during the next eight days, though on the two following days (twenty-second and twenty-third) the turbidity became most obvious: much sediment was deposited, and the fluid assumed a much lighter colour.[49] (On the twenty-second day the temperature of the bath was raised to 100° F., for two or three hours.)
No. IX.—Turnip Infusion remained for four days without undergoing any apparent change. Its neck was then accidentally broken at the fourth joint—a certain amount of fluid still filling the third joint. In this condition the flask was allowed to remain in the water-bath, and the fluid continued quite unchanged in appearance for five days. It was then boiled[50] for three minutes, and the neck of the flask was hermetically sealed whilst the fluid was boiling. The flask being re-immersed in water-bath, the fluid continued quite clear for thirteen days. Its neck was then carefully heated in the spirit-lamp flame till, when red-hot, the rapid inbending of the glass showed that the vacuum was still preserved. This being ascertained, the flask was, after a few minutes, replaced in the bath. The next day the temperature of the bath was allowed to go up to 100° F. for three or four hours, and in the evening the fluid was observed to be very slightly turbid. In two days more (i.e., after sixteen days in vacuo) the turbidity was well marked, and when the fluid was examined microscopically it was found to contain an abundance of very languid Bacteria and Vibriones. On opening the flask there was an outrush of very fœtid gas, and the reaction of the fluid was acid.[51]