Chemistry and Physics. 501 



hydrate. Its composition was determined (1) by weighing the 

 boat before and after converting the calcium into nitride ; and 

 (2) by decomposing a weighed quantity of the nitride with water. 

 Four experiments gave 18-37, 18*21, 18-81 and 18*17 per cent of 

 nitrogen and 81*63, 81*79, 81*19 and 80*49 of calcium ; the formula 

 <J 3 N 2 requiring 18'92 of'N and 8L*08 of Ca. The author thinks 

 that the production of calcium nitride industrially will solve the 

 problem of the manufacture of ammonia from the atmosphere. — 

 C. M., cxxvii, 497-501, October, 1898. g. f. b. 



4. On Sodium sub-oxide and peroxide produced by combus- 

 tion. — The composition and the heat of formation of the sodium 

 oxides produced by combustion has been studied by Forcrand. 

 About 20 grams of sodium was melted in a tubulated glass retort, 

 provided with a spherical condenser, also tubulated; a current of 

 dry air, free from carbon dioxide, being passed through the appa- 

 ratus. A little above its fusing point the sodium became cov- 

 ered with a gray layer, which soon increased to form voluminous 

 arborescent gray masses. If the operation be continued the gray 

 mass takes fire, producing white vapors, which condense both in 

 the retort and the receiver, leaving a yellowish porous mass which 

 becomes nearly white on cooling. The three products were then 

 analyzed. The gray mass gave 81*88 per cent of sodium and 

 €'1512 gram evolved 22*05 cc of hydrogen when placed in water; 

 whence it was composed of 96*26 per cent of the sub-oxide Na 3 

 mixed with 3*74 per cent of sodium. The white snow condensed 

 in the cooled receiver gave 58*13 per cent of sodium, correspond- 

 ing to the formula Na 2 2 , which requires 58*97. The white 

 powder in the retort was also Na 2 2 , with a trace of moisture. 

 The yellowish-white residue gave 61*24 and 60*18 per cent of 

 sodium in two samples ; and hence was a mixture in variable pro- 

 portions of Na 2 and Na 2 2 . Heated again in a current of dry 

 air, it was converted into Na 2 2 with a trace of moisture. No 

 trioxide Na 2 3 apparently was formed in this reaction. 



In a subsequent paper, the author gives the results of his experi- 

 ments to determine the heat of formation of these oxides. He 

 finds for the sub-oxide Na s O, the following equation : 



Na 3 solid + O gas = Na 3 solid + 101*57 cal. 

 For the dioxide, Na 2 2 



Na a solid + 2 gas — Na 2 2 solid -f 119*79 cal. 

 And for the oxide Na 2 



Na a solid + O gas = Na 2 solid + 100*40 cal. 

 — C. R., cxxvii, 364-366, 514-516, August, October, 189S. 



G. F. B. 



5. On Aluminum nitride. — It has been pointed out by Franck 

 that aluminum nitride is obtained when an intimate mixture of 

 finely divided aluminum and calcium carbide is heated in a porce- 

 lain crucible by means of a blast, with free access of air. The 

 product contains 15 to 20 per cent of nitrogen. Moist air decom- 



