A NEW CONSTITUENT OF THE ATMOSPHERE. 233 
concluded from this experiment that silicon, even while being liberated, is without 
action on argon. 
The action of compounds was then tried ; these chosen were such as lead to oxides 
or sulphides. Inasmuch as the platinum-metals, which are among the most inert of 
elements, are attacked by fused caustic soda, its action was investigated. 
(h) Fused and Red-hot Caustic Soda.—The soda was prepared from sodium, in an 
iron boat, by adding drops of water cautiously to a lump of the metal. When action 
had ceased, the soda was melted, and the boat introduced into a piece of combustion- 
tube placed in the circuit. After three hours circulation no contraction had occurred. 
Hence caustic soda has no action on argon. 
(7) Soda-lime at a red-heat.—Thinking that the want of porosity of fused caustic 
soda might have hindered absorption, a precisely similar experiment was carried out 
with soda-lime, a mixture which can be heated to bright redness without fusion. 
Again no result took place after three hours heating. 
(j) Fused Potassium Nitrate was tried under the impression that oxygen plus a 
base might act where oxygen alone failed. The nitrate was fused, and kept at a 
bright red heat for two hours, but again without any diminution in volume of the 
argon. a 
(k) Sodium Peroxide.—Yet another attempt was made to induce combination with 
oxygen and a base, by heating sodium peroxide to redness in a current of argon for 
over an hour, but also without effect. It is to be noticed that metals of the platinum 
group would have entered into combination under such treatment. 
(1) Persulphides of Sodium and Calciwm.—Soda-lime was heated to redness in 
an open crucible, and some sulphur was added to the red-hot mass, the lid of the 
crucible being then put on. Combination ensued, with formation of polysulphides 
of sodium and calcium. This product was heated to redness for three hours in a 
brisk current of argon, again with negative result. Again, metals of the platinum 
group would have combined under such treatment. 
(m) Some argon was shaken in a tube with nitro-hydrochloric acid. On addition 
of potash, so as to neutralise the acid, and to absorb the free chlorine and nitrosyl 
chloride, the volume of the gas was barely altered. The slight alteration was evidently 
due to solubility in the aqueous liquid, and it may be concluded that no chemical 
action took place. 
(7x) Bromine-water was also without effect. The bromine vapour was removed 
with potash. : 
(0) A mixture of potassium permanganate and hydrochloric acid, involving the 
presence of nascent chlorine, had no action, for on absorbing chlorine by means of 
potash, no alteration in volume had occurred. 
(p) Argon is not absorbed by platinum black. A current was passed over a pure 
specimen of this substance ; as usual, however, it contained occluded oxygen. There 
was no absorption in the cold. At 100°, no action took place; and on heating to 
MDCCCXCV.—A. 2H 
