580 FRAGMENTS OF SCIENCE. 
is pierced iu 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 b 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oil-bath is withdrawn, and the liquid, whose putrescibility 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 1 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 
