First Set of Experiments (I.–XV.).
a. Fluid exposed to Air in a Flask with a short Open Neck.
No. I.—Urine in twenty-four hours was still clear and free from deposit. In forty-four hours the fluid was very slightly turbid, and on microscopical examination Bacteria and Torulæ were found, though not in very great abundance. In sixty-eight hours the fluid was quite turbid.
No. II.—Hay Infusion in twenty-four hours was still clear. In forty-four hours the fluid was very turbid, and a drop on examination showed multitudes of Bacteria of different kinds, exhibiting languid movements. In sixty-eight hours the turbidity had become much more marked, and there was also a certain amount of sediment.
No. III.—Turnip Infusion in twenty-four hours showed a very slight degree of turbidity. A drop examined microscopically revealed a number of very minute, but very active, Bacteria. In forty-four hours the turbidity had become very well marked.
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]
d. Fluid in a Flask having a Neck two feet long, bent at right angles shortly above the bulb, and provided with a firm Plug of Cotton-Wool twelve inches in length.
No. X.—Urine remained quite bright and clear during the fifteen days in which it was kept under observation in the water-bath.[52]
No. XI.—Hay Infusion showed a very slight amount of sediment after forty-four hours, which seemed to increase somewhat during the next three days. The fluid afterwards appeared to undergo no further change, though it remained in the warm water-bath for fifteen days.[52]
No. XII.—Turnip Infusion in four days showed a well-marked turbidity, and also very many flakes of a broken pellicle.[52]
e. Fluid (in vacuo) in a Flask, the Neck of which was hermetically Sealed by means of the Blowpipe Flame during Ebullition.
No. XIII.—Urine in forty-four hours showed a very slight amount of sediment. During the next two days the sediment very slightly increased, but was still small in amount. At the expiration of fifteen days, no further increase in the turbidity having taken place, the fluid was examined. The vacuum was still partially preserved, as evidenced by the rapid inbending of a portion of the neck of the flask after it had been carefully made red-hot. When opened, the odour of the fluid was stale, but not fœtid, and its reaction was still faintly acid. On microscopical examination Bacteria and Torulæ were found in tolerable abundance.
No. XIV.—Hay Infusion in forty-four hours showed a very slight amount of turbidity. In sixty-eight hours the turbidity was most marked, and there was also a small amount of sediment. In another twenty-four hours it was noticed that the colour of the fluid had become much lighter, whilst the turbidity and sediment had increased. It subsequently continued in much the same state, and the flask was opened on the sixteenth day. The vacuum was found to be almost wholly impaired, whilst the odour of the fluid was sour, and not at all hay-like. On microscopical examination Bacteria, Vibriones, Leptothrix, and Torulæ, were found in abundance, and the former were very active.
No. XV.—Turnip Infusion after forty-eight hours showed a well-marked turbidity. In seventy-two hours the turbidity was more marked, and there was a slight amount of sediment. The turbidity also increased during the next twenty-four hours; though, after that, the infusion seemed to undergo no further change. The flask remained in the warm bath for fifteen days, when the fluid was examined. Its odour was not fœtid, but was somewhat like that of baked turnip. Bacteria and Vibriones existed in abundance, though their movements were extremely languid.