140 



THE FLOATING-MATTER OF THE AIR. 



Fig, 13. 



were then removed and permitted to cool ; after 

 which the sealed end of each neck was broken off by 

 means of a file, its subsequent appearance being shown 

 at c, fig. 12. The bulbs, protected by the cotton-wool 

 plugs in the neck above them, were then exposed to a 

 tolerably uniform temperature of about 90° Fahr. 



At the same time two similar bulbs, charged with 

 the same infusion, had their necks bent downwards, 

 as in fig. 13, the inclined por- 

 tion being plugged, so that no 

 impurity could fall into the 

 liquid from the cotton-wool. 

 These two bulbs were boiled 

 for five minutes in an oil-bath, 

 and plugged while boiling with 

 cotton-wool. Tliey were then 

 sealed behind the plugs and 

 permitted to cool, their sealed 

 ends being broken off after- 

 wards. 



On the 30th of September 

 the infusion in all the straight- 

 necked bulbs was turbid, while 

 in the two bent-necked ones it 

 was perfectly clear. On the 2nd 

 of October tlie turbidity of the 

 stiaiffht-necked bulbs had in- 

 creased, while a fatty scum had formed on the sur- 

 face of each. The two others were at the same time 

 slightly but distinctly turbid. 



My inference from this experiment was that in 

 neither the straight-necked nor the bent-necked bulbs 

 had the germs been wholly killed by the boiling. The 

 difference Ijetween the results obtained with the re- 

 sijective bulbs arises from the different modes of mani- 



