1898.1 



on Liquid Air as an Analytic Agent. 



826^ 



glass surface maintained at a higher temperature. To separate the 

 true conduction from the radiation and the gas motion would require 

 far more elaborate experiments, but these are sufficient to prove that 

 the presence of certain finely divided solids in the high vacuum space 



Fig. 4. — Three tubes blovvu un to one stem, similar to Fig. 3. 



A, vacuum space having three turns of gold paper, gold outside. B, vacuum 

 space having some pieces of gold leaf put in so as to make contact between walls 

 of vacuum tube. C, vacuum space empty. A', B', C, the same tubes in section. 



of the vessels used in low temperature research improves the heat 

 insulatiou, wh'le in the presence of air the same bodies facilitate the 

 transference of heat. This is the explanation of Pictet's apparently 

 extraordinary results. 



In no case was the diminution of the influx of heat, in the case of 



