64 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



The three series represent hydrochloric acid prepared by three distinct 

 methods. Series I and II are to be corrected by —0.00013 gTainme, 

 which represents gas adsorbed by the walls of the containing glass bulb. 

 The corrected mean becomes 1.64011, =t .00005 grammes, which, at sea 

 level and latitude 45° is equivalent to 1.63915 grammes, the weight of 

 the normal litre. If we reduce this with the critical constants used by 

 Guye and Ter Gazarian," it gives HC1 = 36.4548, and with H = 1.00T8, 

 Cl= 35.4470, ±.0011, a very low value. 



In order to ascertain the atomic weight of chlorine, G-ray and Burt 

 have measured the compressibility of the HCl, and also determined its 

 composition by volume. In the latter case the gas was decomposed by 

 heated aluminum, and the volume of hydrogen liberated from two vol- 

 umes of hydrochloric acid was measured. The volumes thus found were 

 as follows: 



1.00797 



1.00795 



1.00790 



1.00790 



1.00781 



1.00779 



1.00787 



1.00798 



Mean, 1.00790, ± .000017 



Using Morley's value for the weight of a litre of hydrogen, 0.089872, 

 ±.0000028 gramme, and with the atomic weight 11 = 1.00779, ±.00001, 

 the molecular weight of HCl is given by tbe following equation: 



^Sm2XiMm>''-'^™ = ''■'''' 



^ See ante. Gray and Burt do not make Ihis calculation. It is useful, however, tor purposes 

 of comparison. 



