Carbonic Acid on Smooth Glass Surfaces. 167 



or volume v of the gas condensed on the surface of the glass 

 for the time T, as the following observation shows. The 

 weight of the gas in the apparatus is now in four parts — viz. 

 that in vessel A, in the measuring-tube B, in the passage of 6, 

 and the weight g which is condensed on the glass threads in 

 time T. Thus we have 



0-76x773\l + «f + l + *« 1 + atJ J ' 

 and 



a- S I ( P » V " 4- P « Y - I^±\ 



9 0-76x773 \ VI +«<„ l + «* m + l + «tj 



773 

 By multiplying these equations by — - we obtain, in cubic 



s 



centimetres, the volume v (at 0° C. and 0*76 metre pressure 

 of mercury), which during the time T was condensed on the 

 glass threads. If we take then 



1 / P a V„ , F m Y m P»V* \_ A (5) 



076U+*<„ -1 + at^l+atJ ' " ' ^ ' 



then this value remains in all the experiments the same, and 

 we have 



All the observations in the following communication have 

 been calculated according to this simple formula. 



The numerical values for deducing the constant A were :— 



V =169-974 at 35° C, s g =2*5056, p =144*265 ; 



V a =112-397 c.c, P a =0*00099m.,*« = 15°*0 C; 



V h = 0-0478 c.c, P* = 0*7488 in., fc=15°-0 C.; 



Y m = 86-252 c.c, P m = 0-7435 m., * w = 15°-0 C. 



From which 



A=80*172- u=80*172 - (112*445 + V m ). 



A 0Ui ^ 5 l ou iL 0-76(1 + 0*003660 



The surface of the spun glass, 1 metre long, enclosed in the 

 apparatus amounted to 



0*09450 p = 13*623 square metres. 



The experiments were performed in a gas-analysis room spe- 

 cially set apart for the purpose, whose temperature varied 



