128 Dr. Schrocder van dor Kolk on Gases. 



For carbonic acid at 3°, was obtained 



^=[l-A(A-l)-B(/i-l) 2 ]K, 

 A = 0-008567, 

 B = 0-000111, 

 K= 19-0949. 



Volume of 1 kilog. at 0° and 0*760 metre pressure =0*505711 

 cubic metre. At 100°, on the contrary, 



^ 00 =[l-A(/^-l)-B(A-l) 2 ]l-00391 K, 



A =0-002465, 



B= 0000275. 



h always denotes the barometric height in metres ; and as p gives 

 the pressure in kilogrammes, in all cases p = 13595^. Peclct, 

 as is well known, has expressed the opinion that the deviations 

 from Mariotte and Gay-Lussac's law might be caused by ad- 

 hesion of the gases to the glass sides. Such an adhesion 

 undoubtedly takes place; the question is, whether it is of 

 appreciable influence on the formulae obtained. In the first 

 place, the assumption that the deviations arise only from adhe- 

 sion is very improbable, as with vapours in the neighbourhood 

 of the points of condensation deviations do undoubtedly occur, 

 and between gases and vapours a quantitative and not qualita- 

 tive difference is to be assumed. It follows, however, from 

 Regnault's weighings that the errors are as good as impercep- 

 tible. If the weight of a gas contained in a globe at a definite 

 temperature is determined for two different pressures, the second 

 value may be calculated from the first by means of the formula? 

 of interpolation obtained. The condensed gaseous layer only 

 affects the weighing, and not the measurement of the pressure; 

 for this always corresponds to the pressure of the uncondensed 

 gaseous mass. Now Regnault found that the weight of a defi- 

 nite volume of carbonic acid at 100 o, 01 and 755*65 millims. 

 pressure was 14'19 grammes, while at the same temperature, but 

 under a pressure of 338*39 millims., the weight was 6*3587 

 grammes. Now if this value be calculated from the first deter- 

 mination by means of the formulas of interpolation obtained, 

 which are only deduced from the pressures, we get 6*3585 grms., 

 which is almost exactly equal to the value obtained directly*. 



At a lower pressure the weighings at 0° exhibit a small dif- 

 ference, which only amounts, however, to 3000 0I> ^ e magni- 

 tude to be determined : this may arise from the fact that the 

 formula of interpolation developed from higher pressures differs 

 a little in the case of a lower pressure of 0*2 metre. 

 * PoggendorfF's Annalen, vol. cxvi. p. 444. 



