A NEW CONSTITUENT OF THE ATMOSPHERE. 209 
accident occurred, by which no gas could have been lost, but of such a nature that 
from 100 to 200 cub. centims. of air must have entered the working vessel. The gas 
remaining at the close of the large scale operations was worked up as usual with 
battery and coil until the spectrum showed only slight traces of the nitrogen lines. 
When cold, the residue measured 4 cub. centims. This was transferred, and after 
treatment with alkaline pyrogallate to remove oxygen, measured 3°3 cub. centims. 
If atmospheric nitrogen had been employed, the final residue should have been about 
30 cub. centims. Of the 3°3 cub. centims. actually left, a part is accounted for by 
the accident alluded to, and the result of the experiment is to show that argon is not 
formed by sparking a mixture of oxygen and chemical nitrogen. 
In a second experiment of the same kind 5660 cub. centims. of nitrogen from 
ammonium nitrite were treated with oxygen in the large apparatus (fig. 7, § 8). The 
final residue was 3°5 cub. centims.; and as evidenced by the spectrum, it consisted 
mainly of argon. 
The source of the residual argon is to be found in the water used for the 
manipulation of the large quantities of gas (6 litres of nitrogen and 11 litres of 
oxygen) employed. Unfortunately the gases had been collected by allowing them to 
bubble up into aspirators charged with ordinary water, and they were displaced by 
ordinary water. In order to obtain information with respect to the contamination 
that may be acquired in this way, a parallel experiment was tried with carbonic 
anhydride. Eleven litres of the gas, prepared from marble and hydrochloric acid 
with ordinary precautions for the exclusion of air, were collected exactly as oxygen 
was commonly collected. It was then transferred by displacement with water to a 
gas pipette charged with a solution containing 100 grms. of caustic soda. The 
residue which refused absorption measured as much as 110 cub. centims. In another 
experiment where the water employed had been partially de-aerated, the residue left 
amounted to 71 cub. centims., of which 26 cub. centims. were oxygen. The 
quantities of dissolved gases thus extracted from water during the collection of 
oxygen and nitrogen suffice to explain the residual argon of the negative experiments. 
It may perhaps be objected that the impurity was contained in the carbonic 
anhydride itself as it issued from the generating vessel, and was not derived from the 
water in the gas-holder ; and indeed there seems to be a general impression that it is 
difficult to obtain carbonic anhydride in a state of purity. To test this question, 
18 litres of the gas, made in the same generator and from the same materials, were 
passed directly into the absorption pipette. Under these conditions, the residue was 
only 64 cub. centims., corresponding to 4 cub. centims. from-11 litres. The quantity 
of gas employed was determined by decomposing the resulting sodium carbonate with 
hydrochloric acid, allowance being made for a little carbonic anhydride contained in 
the soda as taken from the stock bottle. It will be seen that there is no difficulty 
in reducing the impurity to sjgoth, even when india-rubber connections are freely 
used, and no extraordinary precautions are taken. The large amount of impurity 
MDCCCXCV.—A, 25 
