Phenomena of Putrefaction and Infection. 65 



of the aperture closed by the india-rubber secures the free lateral 

 play of the lower end- of the pipette, Into two other smaller aper- 

 tures in the top of the cupboard are inserted, air-tight, the open 

 ends of two narrow tubes, intended to connect the interior space 

 with the atmosphere. The tubes are bent several times up and 

 down, so as to intercept and retain the particles carried by such 

 feeble currents as changes of temperature might cause to set in 

 between the outer and the inner air. 



The bottom of the box is pierced, sometimes with two rows, some- 

 times with a single row of apertures, in which are fixed, air-tight, 

 large test-tubes, intended to contain the liquid to be exposed to 

 the action of the moteless air. 



On the 10th of September the first case of this kind was closed. 

 The passage of a concentrated beam across it through its two side 

 windows then showed the air within it to be laden with floating 

 matter. On the 13th it was again examined. Before the beam 

 entered and after it quitted the case its track was vivid in the 

 air, but within the case it vanished. Three days of quiet sufficed 

 to cause all the floating matter to be deposited on the sides and 

 bottom, where it was retained by a coating of glycerine, with 

 which the interior surface of the case had been purposely varnished. 

 The test-tubes were then filled through the pipette, boiled for five 

 minutes in a bath of brine or oil, and abandoned to the action of 

 the moteless air. During ebullition aqueous vapour rose from 

 the liquid into the chamber, where it w r as for the most part con- 

 densed, the uncondensed portion escaping, at a low temperature, 

 through the bent tubes at the top. Before the brine was removed 

 little stoppers of cotton-wool were inserted in the bent tubes, lest 

 the entrance of the air into the cooling chamber should at first be 

 forcible enough to carry motes along with it. As soon, however, 

 as the ambient temperature was assumed by the air within the case 

 the cotton-wool stoppers were removed. 



"We have here the oxygen, nitrogen, carbonic acid, ammonia, 

 aqueous vapour, and all the other gaseous matters which mingle 

 more or less with the air of a great city. "We have them, more- 

 over, " untortured n by calcination and unchanged even by filtra- 

 tion or manipulation of any kind. The question now before us 

 is, can air thus retaining all its gaseous mixtures, but self -cleansed 

 from mechanically suspended matter, produce putrefaction ? To 

 this question both the animal and vegetable worlds return a decided 

 negative. 



Among vegetables experiments have been made with hay, tur- 

 nips, tea, coffee, hops, repeated in various ways with both acid 

 and alkaline infusions. Among animal substances are to be men- 

 tioned many experiments with urine ; while beef, mutton, hare, 

 rabbit, kidney, liver, fowl, pheasant, grouse, haddock, sole, salmon, 

 cod, turbot, mullet, herring, whiting, eel, 0} r ster have been all sub- 

 jected to experiment. 



- The result is that infusions of these substances exposed to the 

 common air of the Royal Institution laboratory, maintained at a 



Phil. Mag. S. 5. Vol. 2. No. 8. July 1876. F 



