A NEW CONSTITUENT OF THE ATMOSPHERE. UL 
The mean result of the weight of 1 litre of “chemical” nitrogen has been found 
to equal 1:2511. It is therefore seen that “chemical” nitrogen, derived from 
“atmospheric” nitrogen, without any exposure to red-hot copper, possesses the 
usual density. 
Experiments were also made, which had for their object to prove that the ammonia, 
produced from the magnesium nitride, is identical with ordinary ammonia, and 
contains no other compound of a basic character. For this purpose, the ammonia 
was converted into ammonium chloride, and the percentage of chlorine determined 
by titration with a solution of silver nitrate which had been standardized by titrating 
a specimen of pure sublimed ammonium chloride. The silver solution was of such a 
strength that 1 cubic centim. precipitated the chlorine from 0°001701 gram. of 
ammonium chloride. ; 
1. Ammonium chloride from orange-coloured sample of magnesium nitride. 
01106 gram. required 43°10 cub. centims. of silver nitrate = 66°35 per cent. of 
chlorine. 
2. Ammonium chloride from blackish magnesium nitride. 
0°1118 gram. required 43°6 cub. centims. of silver nitrate = 66°35 per cent. of 
chlorine. 
3. Ammonium chloride from nitride containing a large amount of unattacked 
magnesium. 
00630 gram. required 24°55 cub. centims. of silver nitrate = 66°30 per cent. of 
chlorine. 
Taking for the atomic weights of hydrogen, H = 1:0032, of nitrogen, N = 14:04, 
and of chlorine, Cl = 35°46, the theoretical amount of chlorine in ammonium chloride 
is 66°27 per cent. 
From these results—that nitrogen prepared from magnesium nitride obtained by 
passing “atmospheric” nitrogen over red-hot magnesium has the density of 
“chemical” nitrogen, and that ammonium chloride prepared from magnesium nitride 
contains practically the same percentage of chlorine as pure ammonium chloride—it 
may be concluded that red-hot magnesium withdraws from “atmospheric” nitrogen 
no substance other than nitrogen capable of forming a basic compound with hydrogen. 
In a subsequent part of this paper, attention will again be called to this 
statement. (See addendum p. 240.) 
2. Reasons for Suspecting a hitherto Undiscovered Constituent in Arr. 
When the discrepancy of weights was first encountered, attempts were naturally 
made to explain it by contamination with known impurities. Of these the most 
likely appeared to be hydrogen, present in the lighter gas, in spite of the passage over 
red-hot cupric oxide. But, inasmuch as the intentional introduction of hydrogen 
into the heavier gas, afterwards treated in the same way with cupric oxide, had no 
effect upon its weight, this explanation had to be abandoned; and, finally, it became 
