142 THE FLOATING-MATTEE OF THE AIR. 



for five minutes. Before the ebullition ceased, the 

 neck of each was stopped with a plug of cotton-wool. 



Up to October 6th all the bulbs continued clear. 

 On the 6th one bulb of the series last described be- 

 came turbid, lighter in colour than its neighbours, and 

 covered with a fatty scum. On the 7th one tube of the 

 first series (boiled after the fashion of Eoberts for ten 

 minutes) also became turbid and exhibited the same 

 fatty scum. The remaining ten bulbs maintained per- 

 manently their deep brown-sherry colour, their high 

 transparency, and their perfect freedom from Bacterial 

 life. They are still clear, though seven months have 

 elapsed since their preparation. 



In the great majority of these experiments the de- 

 portment of alkalized hay-infusion contradicts that 

 observed by Dr. Roberts and Professor Cohn. 



Six other pipette-bulbs, with their necks so bent 

 and plugged with cotton-wool and asbestos that no 

 impurity falling from the plug could reach the infusion, 

 were also charged on the 2nd of October. Three of the 

 bulbs, with their necks hermetically sealed, were main- 

 tained for ten minutes at the temperature of boiling 

 water, the sealed ends being afterwards broken off. 

 The three other bulbs were boiled in an oil-bath, and 

 had their necks plugged before ebullition ceased. All 

 six bulbs have remained perfectly transparent up to the 

 present time. 



Here, again, we have discordance between my re- 

 sults and those of Dr. Roberts and Professor Cohn. 



But on tlie 6th of October another infusion was 

 prepared and neutralized, exactly in the same fashion 

 as before. Five pipette-bulbs were charged with it; 

 they were hermetically sealed and maintained at the 

 boiling temperature for ten minutes. The sealed ends 

 were afterwards broken off, and the bulbs exposed to a 



