270 The Integral Weight of Water. 



on Integral Weights in Chemistry, in this Magazine for 

 October 1837, it was stated that a litre of hydrogen gas " at 

 0° and 760 millim. being assumed as a unit of volume for 

 all species, the weight of a litre of any other gas or vapour at 

 the standard temperature and pressure is its integral weight. 

 In like manner the integral weight of a liquid species is the 

 weight of the same volume at its boiling-point under a pres- 

 sure of 760 millim The weights thus obtained for 



equal volumes of the various liquid and solid species, as well 

 as for the gaseous species, are evidently the specific gravities 

 of these species ; that of hydrogen at the standard temperature 

 and pressure being unity (H 3 = 2'0). They are at the same 

 time the integral weights of the species compared." 



Notwithstanding this clear statement in both papers that it 

 is hydrogen gas at 0° and 760 millim. which is to serve as the 

 unit of specific gravity alike for gaseous, liquid, and solid 

 species, the reader will find in these papers, and also in the 

 first edition of the author's ' New Basis for Chemistry' (1887), 

 an error in the subsequent calculations. The problem having 

 been approached from the comparison of the weights of equal 

 volumes of liquid water at 0° and 100°, and of water-vapour 

 at 100° and 760 millim., by an inadvertence (until now un- 

 perceived) the weights alike of hydrogen gas and of water- 

 vapour at the latter temperature were substituted for their 

 weights at 0° and 760 millim., thus leading to a grave error 

 in the figure given for the integral weight of liquid water, 

 and of bodies for which it serves as the unit of specific gravity, 

 and making it equal to 29244. In fact, however, taking as 

 the unit of weight that of the litre of hydrogen gas at standard 

 temperature and pressure (0°and 760 millim.), and comparing 

 it with that of liquid water at 100° (its temperature of forma- 

 tion at 760 millim.), when a litre of it weighs 958-78 grammes, 

 we have 



0-0896 : 958-78 : : 2 : 0=21400-3. 



This value is, then, alike the specific gravity of the liquid 

 on the hydrogen basis, and its integral weight, which, if we 

 take H 2 = 17*96, corresponds very closely to 1192 (H 2 0) = 

 21408 ; ice_ being probably 1094 (H 2 0) , calcite 584 (CCa0 3 ), 

 and aragonite 630 (CCa0 3 ). While the writer regrets this 

 error in calculation, made in direct contradiction to the prin- 

 ciples laid down by him in both of the papers cited, it will be 

 seen that its correction in no way affects their argument, 

 which he hopes to develop further at an early day. 



Washington, D.C., 



February 22, 1888. 



