111 



DIRECT PROPERTIES OF MOLECULES 



303 



which form it ; for if this law holds for single molecules, 

 then by Avogadro's law it will hold too for the magni- 

 tudes Q which represent the sum of the sections of all the 

 molecules in unit volume. As a test of this supposition I 

 have calculated the most probable values of the sum of the 

 sections of the simple atoms by combining the values 

 found for molecules consisting of only two atoms by the 

 method of least squares, and have obtained the values 



H=5082, = 8877, N = 9513, = 9796, 

 01 = 19513. 



By the help of these values, together with those for H 2 S 

 and S0 2 , I have also obtained for the sulphur atom the 

 mean value 



S = 19617. 



I have finally from these atomic sections deduced for the 

 compound gases the following molecular sections, which for 

 comparison are tabulated in the column marked ' calculated,' 

 against those given in the former table, and here marked 



' observed.' 



Values of Q. 



The two columns exhibit an excellent agreement in the 

 earlier part of the table, but none at all for the last seven 



