SPONTANEOUS GKNRIUTION. 





\\ have now to devise a means of testing the action of 



j)ontaneously purified air upon putrescible infusions. 



\\ <",<len chambers, or cases, are accordingly constn 



liaving glass fronts, side-windows, and back-doors. 



Through tli' bottoms of the chambers test-tubes pass air- 



tight; their open ends, for about one-fifth of the length of 



the tubes, being within the chambers. Provision \* 



f-<r a free connection through sinuous channels between 



tin; i: i the outer air. Through such channels. 



though open, no djist will reach the chat 



each chamber is perforated by a circular hoi.- t\\. 



diameter, closed air-tight by a sheet of india rubber. Thi.s 



