196 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
by WoxtER and DeEvILLE ;* they passed a mixture of the vapour of titanium chloride 
and nitrogen over red-hot aluminium, and obtained a large yield of nitride. It is 
possible that a mixture of the precipitated oxide of titanium with magnesium dust 
might be an effective absorbing agent at a comparatively low temperature. [Since 
writing the above we have been informed by M. Moissan that titanium, heated to 
800°, burns brilliantly in a current of nitrogen. It might therefore be used with 
advantage to remove nitrogen from air, inasmuch as we have found that it does not 
combine with argon.—April, 1895.] 
(d.), (e.) Lithium at a dull red heat absorbs nitrogen,t but the difficulty of 
obtaining the metal in quantity precludes its application. On the other hand, 
strontium and barium, prepared by electrolysing solutions of their chlorides in 
contact with mercury, and subsequently removing the mercury by distillation, are 
said by MAaQuENNE| to absorb nitrogen with readiness. Although we have not tried 
these metals for removing nitrogen, still our experience with their amalgams has led 
us to doubt their efficacy, for it is extremely difficult to free them from mercury by 
distillation, and the product is a fused ingot, exposing very little surface to the action 
of the gas. The process might, however, be worth a trial. 
Barium is the efficient absorbent for nitrogen when a mixture of barium carbonate 
and carbon is ignited in a current of nitrogen, yielding cyanide. Experiments have 
shown, however, that the formation of cyanides takes place much more readily and 
abundantly at a high temperature, a temperature not easily reached with laboratory 
apphances. Should the process ever come to be worked on a large scale, the gas 
rejected by the barium will undoubtedly prove a most convenient source of argon. 
(f.) Nitride of magnesium was prepared by DevintLEe and Caron (loc. cit.) during 
the distillation of impure magnesium. It has been more carefully investigated by 
BRIEGLEB and GEUTHER,§ who obtained it by igniting metallic magnesium in a 
current of nitrogen. It forms an orange-brown, friable substance, very porous, and 
it is easily produced at a bright red heat. When magnesium, preferably in the form 
of thin turnings, is heated in a combustion tube in a current of nitrogen, the tube is 
attacked superficially, a coating of magnesium silicide being formed. As the temperature 
rises to bright redness, the magnesium begins to glow brightly, and combustion takes 
place, beginning at that end of the tube through which the gas is introduced. The 
combustion proceeds regularly, the glow extending down the tube, until all the metal 
has united with nitrogen. The heat developed by the combination is considerable, 
and the glass softens; but by careful attention and regulation of the rate of the 
current, the tube lasts out an operation. A piece of combustion tubing of the usual 
length for organic analysis packed tightly with magnesium turnings, and containing 
* © Annalen der Chemie u. Pharmacie,’ 73, 34. 
+ Ovvrarp, ‘Comptes Rendus,’ 114, 120. 
ft Otyrarp, ‘ Comptes Rendus,’ 114, 25, and 220. 
§ ‘Annalen der Chemie u. Pharmacie,’ 123, 228. 
