ARGON, A NEW CONSTITUENT OF THE ATMOSPHERE. 5 



whicli li:ul [ireviously been boiled, so as at all events partially to exjiel air. The 

 uitrogen passed into the vacuous gl(jl)e through a solution of potassium hydroxide, 

 and through two drying tubes, one containing soda-linic, and the <itlicr, phosphoric 

 anhj'dride. 



At 18.38° C, and 754.4 mm. pressure, l(')2.84r) c. c. of this nitnxjjen weighed 

 0.18963 gramme. Hence, 



Weight of 1 litre at (»" C. and 7('>(> nun. piessure, 1.2521 gramme. The 

 mean result of the weight of 1 litre of "chemical" nitrogen has been found 

 to e((ual 1.2505. It is therefore seen that "chcmicar' nitroiren, derived from 

 "atmospheric" nitrogen, without any exjx)sure to I'edliot copj^ier, possesses the 

 usual density. 



E.xperiments were also made, which had for their object to prove that the 

 ammonia, produced fi'oni tlie magnesium nitiide, is identical with ordinary ammonia, 

 and contains no other compound of a basic charactei'. For this purpose, the am- 

 monia was converted into ammonium chloride, and the percentage of chloi'ine 

 determined by titration with a solution of silver nitrate which had been standard- 

 ized by titi'ating a specimen of pure sublimed ammonium chloride. The silver 

 solution was of such a strength that one cubic centimetre precipitated the chlorine 

 from 0.001701 gi-amme of ammonium chloride. 



I. Ammonium chloi'ide from orangecoloi'ed sample of magnesium nitride. 



0.1106 gramme re(]uiie<l 43. lu cubic centimetres of silver nitrate, = 66.35 

 p. c. of chlorine. 



II. Anunonium chloi'ide from blackish magnesium nitride. 



0.0118 gramme required 43.6 cubic centimetres of silver nitrate, = 66.35 

 p. c. of chlorine. 



III. Ammonium chloride from niti'ide containing a huge amount of unattacked 

 magnesium. 



0.0630 gramme required 24.55 cubic centimetres of silver niti'ate, = 66.30 

 p. c. of chloiine. 



Taking for the atomic weights : of hydrogen, II = 1.0032 ; of nitrogen, N = 

 14.04 ; and of chlorine, CU = 35.46, the theoretical amount of chlorine in anunonium 

 chloi'ide is 66.27 p. c. 



From these results — nitrogen pi'epared 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 

 chloi'ide — it may be concluded that red-hot magnesium withdraws from " atmos- 

 pheric" nitrogen no substance capable of forming a basic compound with hydrogen. 



