194 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
could do, and to a certain extent resolves, the question above suggested. . The 
passage is so important that it will be desirable to quote it at full length. 
“ As far as the experiments hitherto published extend, we scarcely know more of 
the phlogisticated part of our atmosphere than that it is not diminished by lime- 
water, caustic alkalies, or nitrous air; that it is unfit to support fire or maintain life 
in animals; and that its specific gravity is not much less than that of common air ; 
so that, though the nitrous acid, by being united to phlogiston, is converted into air 
possessed of these properties, and consequently, though it was reasonable to suppose, 
that part at least of the phlogisticated air of the atmosphere consists of this acid 
united to phlogiston, yet it was fairly to be doubted whether the whole is of this 
kind, or whether there are not in reality many different substances confounded 
together by us under the name of phlogisticated air. I therefore made an experiment 
to determine whether the whole of a given portion of the phlogisticated air of the 
atmosphere could be reduced to nitrous acid, or whether there was not a part of a 
different nature to the rest which would refuse to undergo that change. The fore- 
going experiments indeed in some measure decided this point, as much the greatest 
part of the air let up into the tube lost its elasticity; yet as some remained 
unabsorbed it did not appear for certain whether that was of the same nature as the 
rest or not. For this purpose I diminished a similar mixture of dephlogisticated and 
common air, in the same manner as before, till it was reduced to a small part of its 
original bulk. I then, in order to decompound as much as I could of the phlogisti- 
cated air which remained in the tube, added some dephlogisticated air to it and 
continued the spark until no further diminution took place. Having by these means 
condensed as much as I could of the phlogisticated air, I let up some solution of liver 
of sulphur to absorb the dephlogisticated air; after which only a small bubble of air 
remained unabsorbed, which certamly was not more than y}9 of the bulk of the 
phlogisticated air let up into the tube; so that, if there is any part of the phlogisti- 
cated air of our atmosphere which differs from the rest, and cannot be reduced to 
nitrous acid, we may safely conclude that it is not more than 73> part of the whole.” 
Although CAVENDISH was satisfied with his result, and does not decide whether 
the small residue was genuine, our experiments about to be related render it not 
improbable that his residue was really of a different kind from the main bulk of the 
“ phlogisticated air,” and contained the gas now called argon. 
CAVENDISH gives data* from which it is possible to determine the rate of absorption 
of the mixed gases in his experiment. The electrical machine used “was one of 
Mr. NairNe’s patent machines, the cylinder of which is 123 inches long and 7 in 
diameter. A conductor, 5 feet long and 6 inches in diameter, was adapted to it, and 
the ball which received the spark was placed two or three inches from another ball, 
fixed to the end of the conductor. Now, when the machine worked well, Mr. Gruprn 
supposes he got about two or three hundred sparks a minute, and the diminution of 
* ‘Phil. Trans.,’ vol. 78, p. 271, 1788. 
