114 



COMPRESSIBILITY OF GASES. 



of the air under pressure, while the pressures stated 

 in atmospheres is to be found in the second, and the 

 pressures required by Boyle's law in the third. 



1 



1 



1 





5.5 



4.930 



5.5 



2 



1.957 



2 





6 



5.342 



6.0 



3 



2.846 



3 





7.62 



6.490 



7.62 



4 



3.737 



4 











Robinson also experimented with air containing vapor 

 of water and in another case with air containing the va- 

 por of camphor. In every case his figures indicated 

 marked deviations from those required by the law. But 

 on the other hand the law commended itself by its mathe- 

 matical simplicity, while the experiments could lay no 

 claim to be considered perfect, and the apparent devia- 

 tions were small. Hence, the experimental results ob- 

 tained by Sulzer and Robinson failed to seriously impair 

 confidence in it, and Boyle's law was still generally held 

 to be the expression of an absolute truth until 164 years 

 after its discovery. 



despretz 1 — 1825. 



But in 1825 the problem was stated by Despretz in a 

 novel form and attacked by a method entirely new. All 

 previous experiments had been made on air. Admit that 

 Boyle's law is rigorously true for air, is it likewise true 

 for other gases? This question Despretz seems to have 

 been the first to ask ; assuredly he was the first to answer 



it- 

 Taking several tubes as nearly alike as possible, and 

 inverting them all in a vessel of mercury, he filled one 

 with air and each of the others with a different gas 



1 Bulletin de Sciences, torn. viii. 

 Annales de Chernie et de Physique, 2d series, torn, xxxiv. 



66 



