202 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
This result was encouraging, although weighted with the unavoidable error attach- 
ing to the weighing of a very small amount. Still the fact remains that the supposed 
nitrogen was heavier than air. It would hardly have been possible to make a mistake 
of 2°7 milligrams. 
It is right here to place on record the fact that this frst experiment was to a great 
extent carried out by Mr. Percy Wixt1Ams, to whose skill in manipulation and great 
care its success is due, and to whom we desire here to express our thanks. 
Experiments were now begun on a larger scale, the apparatus employed being shown 
in figs. 3 and 4. 

A and B are large glass gas-holders of about 10 litres capacity. C is an arrange- 
ment by which gas could be introduced at will into the gas-holder A, either by means 
of an india-rubber tube slipped over the open end of the U-tube, or, as shown in the 
figure, from a test-tube. The tube D was half filled with soda-lime (a), half with 
phosphoric anhydride (b). Similarly, the tube E, which was kept at a red heat by 
means of the long-flame burner, was filled half with very porous copper (a), reduced 
from dusty oxide by heating in hydrogen, half with copper oxide in a granular form (0). 
The next tube, F, contained granular soda-lime, while G contained magnesium turn- 
numbers is taken, that of Recnavitr for nitrogen being omitted, as there is reason to believe that 
his specimen was contaminated with hydrogen. 



Air. | Oxygen. Nitrogen. Hydrogen. 
| 142961 1:25749 0:08991 
| 


This ratio gives for air the composition by volume— 
Oxyreny 7.) 10 an ene ee Oxo percents 
INE Bho 6) 5 5 9 4 0 (AHO 5 
a result verified by experiment. 
It is, of course, to be understood that these densities of nitrogen refer to atmospheric nitrogen, 
that is, to air from which oxygen, water vapour carbon dioxide, and ammonia have been removed. 
