

VOLUMES OF ATOMS IN THE GASEOUS STATE. 



131 



vity of oxygen be made 1 or 1000, the relation of densities to 

 atomic weights will still be very obvious. 



The combining measures of compound gases, although va- 

 riable, have still a constant and a simple relation to each other, 

 such as 1 to 1, 1 to 2, or 2 to 3 ; their elements in combining 

 suffering either no condensation or a definite and very simple 

 change of volume. Hence the density of a compound gas may 

 often be calculated with more precision from the densities of 

 its constituents and a knowledge of the change of volume, if 

 any, which occurred in combination, than it can be determined 

 by experiment. 



To deduce on this principle the specific gravity of steam. 

 It consists of single equivalents of oxygen and hydrogen, of 

 which the combining measure of the first is one, and that of 

 the second two volumes. These three volumes, weigh 1 102. 6 + 

 69 + 69=1240.6, and they form two volumes of steam; of 

 which one volume must, therefore, weigh 1240.6 divided by 

 two, or 620.3, which is, consequently, the calculated specific 

 gravity of steam, referred to that of air as 1000. The rela- 

 tions in volume of the gases before and after combination may 

 be thus exhibited. 



Combining measure, or 

 one volume of oxygen. 



Combining measure, or Combining measure, or 

 two volumes of hydrogen. two volumes of steam. 



1240.6 1240.6 



It thus appears necessary to inscribe 620.3 in each volume of 

 steam, to make up 1240.6, the known weight of the two volumes. 

 In the formation of the hydrochloric acid, equal measures of 

 chlorine and hydrogen unite without condensation, so that the 

 product possesses the united volumes of its constituent gases. 



Combining measure Combining measure Combining measure of 



of hydrogen or two of chlorine or two hydrochloric acid or four 



5078 



5078 



K 2 



