484 M. R. Pictet on the Application of the Mechanical 



Liquid. 



Water 



Alcohol 



; Sulphide of carbon 



Sulphuric ether 



i Chloroform 



Benzine 



Chlorhydric ether 



i Essential oil of turpeniine 



Mercury 



Sulphurous acid 



Boiling- 

 point. 



100 



78-21 



46 



35 



60 



80 



10 



155 



350 



■ 10 



\ calcu- 

 lated. 



5339 



210 

 84 



9012 

 60-73 

 92-9 

 928 

 65-6 

 716 

 94-2 



\ob. 

 served. 



536 



21405 

 8354 

 89-76 

 61 



92-26 

 921 



77 

 94-5 



Derivate 



00346 



00325 



03189 



003563 



0-03337 



003000 



003779 



00261 



002049 



004374 



It is easy to see the perfect coincidence which exists betwen 

 the results of our hypothesis and those furnished by experi- 

 ment. The deviations are very slight, and are readily explained 

 by the anomalies of Mariotte's law and the errors of observa- 

 tion, of which no account was taken in our equations. 



The column of derivates shows that the value of 



(?) 



t'-t 



for 



P=760 and t' — t increases with the volatility of the liquids ; 

 we can represent with sufficient exactness the values of this 

 derivate by 



D 



t'-t 



= K 



274 



274 + t 



(V.) 



Applying this formula (V.) to the liquids mentioned in the 

 preceding Table, we have : — 



Liquid. 



Boiling- 

 point. 



Derivate. 



Value of K. 



Water 



o 



100 

 78-21 

 46 

 35 



0346 0-045 

 00325 0-042 

 003189 ! 0-039 

 0025F3 0040 



Alcohol 



Sulphide of carbon 







60 002337 ! 0040 



Benzine 



80 



0-03000 



0040 

 0-040 

 0040 

 0044 



Chlorhydric ether 



10 

 155 



350 

 - 10 



003779 

 00261 

 002049 

 004374 



Essential oil of turpentine . . . 

 Mercury 



Sulphurous acid 



0041 



274 + £ 

 Thus the factor - - multiplying the derivate of the pres- 



sures with respect to the temperatures gives a constant quan- 



