580 FRA OMENTK OF SCIKNVfl. 



is pierced in the middle by a pin, and through the pin-hole 

 is pushed the shank of a long pipette, ending above in a 

 small funnel. The shank also passes through a stuffing- 

 box of cotton-wool moistened with glycerine; so that, 

 tightly clasped by the rubber and wool, the pipette is not 

 likely in its motions up and down to carry any dust into 

 the chamber. The annexed woodcut shows a chamber, 

 with six test-tubes, its side-windows w w, its pipette p c, 

 and its sinuous channels a Z which connect the air of the 

 chamber with the outer air. 



The chamber is carefully closed and permitted to remain 

 quiet for two or three days. Examined at the beginning 

 by a beam sent through its windows, the air is found laden 

 with floating matter, which in three days has wholly dis- 

 appeared. To prevent its ever rising again, the internal 

 surface of the chamber was at the outset coated with 

 glycerine. The fresh but putrescible liquid is introduced 

 into the six tubes in succession by means of the pipette. 

 Permitted to remain without further precaution, every one 

 of the tubes would putrefy and fill itself with life. The 

 liquid has been in contact with the dust-laden air outside 

 by which it has been infected, and the infection must be 

 destroyed. This is done by plunging the six tubes into a 

 bath of heated oil and boiling the infusion. The time 

 requisite to destroy the infection depends wholly upon its 

 nature. Two minutes' boiling suffices to destroy some 

 contagia, whereas two hundred minutes' boiling fails to 

 destroy others. After the infusion has been sterilized, the 

 oil-bath is withdrawn, and the liquid, whose putrescibility 

 has been in no way affected by the boiling, is abandoned to 

 the air of the chamber. 



With such chambers I tested, in the autumn and winter 

 of 1875-6, infusions of the most various kinds, embracing 

 natural animal liquids, the flesh and viscera of domestic 

 animals, game, fish and vegetables. More than fifty 

 chambers, each with its series of infusions, were tested, 

 many of them repeatedly. There was no shade of uncer- 

 tainty in any of the results. In every instance we had, 

 within the chamber, perfect limpidity and sweetness, which 

 in some cases lasted for more than a year without the 

 chamber, with the same infusion, putridity and its charac- 

 teristic smells. In no instance was the least countenance 

 lent to the notion that an infusion deprived by heat of its 



