152 THE FLOATING-MATTEE OF THE AIR. 



while in the other chamber the three tubes remained 

 sensibly clear and free from scum. Nor did the three 

 tubes of the single chamber charged with the new 

 Heathfield acid infusion present the same appearance ; 

 for while one tube became thickly turbid, the other two 

 remained perfectly pellucid. 



Amid this confusion, the only point worth dwelling 

 on is, that while no single case of escape occurred with 

 the old-hay infusion, whether acid or neutral, with the 

 infusions of both dried and undried new hay a certain 

 percentage of the tubes remained sterile. 



Eeflection on these results naturally drew suspicion 

 upon the chambers. They had been used before, and, 

 though carefully cleansed, some unobserved som*ce of 

 infection may have clung to them. This, at all events, 

 seemed the most rational way of accounting for the 

 differences observed between samples of the self-same 

 infusion placed in different chambers. Hence my desire 

 to expose a fresh series of infusions in chambers which 

 had never been used before. 



Six new ones were therefore constructed, each of 

 them containing six tubes. These were charged on the 

 3rd of November with infusions of old London hay, 

 old Heathfield hay, new London hay, and dried London 

 hay. Two chambers were devoted to each infusion, 

 which in the one chamber was neutralized and in the 

 other unneutralized. 



The six tubes in each chamber were arranged in two 

 rows of three tubes each. Those nearest to the glass 

 front were called the front tubes, the others the back 

 tubes. The infusion intended for the unneutralized 

 chamber was unboiled before its introduction into the 

 three back tubes, and boiled in those tubes for five 

 minutes afterwards ; the infusion for the front tubes was 



