302 report— 1879. 



MONDAY, AUGUST 25, 1879. 



The following Papers were read : — 



1. On the Constitution of Aluminic Compounds. 

 By Professor Odling, F.R.S. 



2. On the Presence of Nitrogen in Steel. By A. H. Allen, F.G.S. 



The author made some preliminary experiments on this suhject in 1872, hut has 

 only recently obtained any definite results. The method adopted has been to 

 dissolve the steel in hydrochloric acid, by which means any combined nitrogen 

 may be presumed to be converted into ammonia. The solution obtained was then 

 distilled with excess of lime, and the distillate examined for ammonia by Nessler's 

 method. The employment of this extremely delicate test enabled the author to 

 operate on a much smaller quantity of steel than was employed by previous 

 investigators. Very special precautions were taken to obtain the hydrochloric acid 

 and other materials free from any trace of ammonia or nitrous compounds, and 

 the air was entirely expelled from the apparatus before commencing the operation. 

 The hydrogen evolved was freed from any traces of ammonia by passing it through 

 a tube filled with glass beads moistened with hydrochloric acid. It was proved by 

 blank experiments that no source of ammonia existed in the reagents or apparatus. 

 When absolutely pure materials were used, and every precaution taken to get rid 

 of the contained air and other sources of error, the addition of Nessler's solution 

 to the liquid obtained on distilling with lime caused a very marked yellowish- 

 brown colouration. On comparing the tint produced with that yielded by a dilute 

 solution of ammonium chloride of known strength, results were arrived at repre- 

 senting the proportions of nitrogen present in various typical specimens of steel. 

 As the results obtained from steels of different kinds varied greatly, it cannot be 

 assumed that there was a constant source of error in the mode of manipulation ; 

 while as the same samples gave substantially concordant results on repeating the 

 experiment, the figures obtained were not the result of accident, but were true 

 expressions of the proportions of nitrogen present. 



In order to obtain ammonia in quantity sufficient for its recognition by other 

 reactions than that with Nessler's test, the following plan was employed : — Steam, 

 generated by boiling water in a flask, was passed over a considerable quantity of steel 

 borings contained in a combustion tube, which was bent beyond the furnace, and 

 prolonged so as to form the inner tube of a Liebig's condenser. To the further end 

 a tube filled with glass beads and furnished with a glass stopcock was attached. A 

 rapid current of steam was driven through the apparatus for a considerable time 

 to expel every trace of air. On condensing the steam it was found free from any 

 trace of ammonia. The steel borings were then heated to redness by a com- 

 bustion furnace, and a rapid current of water passed through the condenser. 

 The condensed steam, when tested by Nessler's solution, was found to contain 

 abundance of ammonia, which did not diminish in amount till the borings were 

 almost entirely oxidised. On redistilling the condensed steam, a distillate was 

 obtained having a distinctly alkaline reaction to litmus paper, and on treating it 

 with hydrochloric acid and platinic chloride a sensible amount of yellow pre- 

 cipitate was obtained, having the characteristic crystalline form of ammonium 

 chloroplatinate. The amount found was larger than could possibly have been 

 produced had the whole of the nitrogen of any residual trace of air been converted 

 into ammonia. The author regards the results now recorded as preliminary merely, 

 and proposes to extend the research to various classes of steel and iron, and 



