716 EEPORT— 1893. 



coated witli cliloride of silver, doubtless from the chlorides in the soil, and contained 

 6*5 per cent, of copper and 1-44 per cent, of gold. 



At Illahun, in Egypt, some beads or buttons were found which proved to be of 

 metallic antimony badly reduced from the sulpliide. They date back to about 

 800 B.C. 



2, Bejport on International Standards for the Analysis of Iron and Steel. 



See Reports, p. 437. 



3. On Native Iron Manufacture in Bengal. By H. Harris and T. Turner. 



4. On Nitride of Iron. By G. J. Fowler, M.Sc. 



This research was undertaken with the object of repeating and extending the 

 work of Stahlschmidt ('Pogg. Ann.,' v. cxxv., 1865, p. 37) on the same subject, 

 his results differing in many points from those of his predecessors. 



The best way of preparing nitride of iron was found to be the following : — Iron 

 is reduced from the hydrate by hydrogen, in a tube of such dimensions that it can 

 be weighed, together with its contents, and thus the end of the reaction deter- 

 mined without exposing the iron to the air. AVhen complete reduction has been 

 eftected, the iron is heated in a fairly rapid current of ammonia gas, until no further 

 increase in weight is observed. The temperature should be kept a little above the 

 melting-point of lead. 



The product obtained when the reaction was complete was analysed. The 

 nitrogen was determined by dissolving the substance in hydrochloric acid, evapo- 

 rating with platinum chloride, and weighing the ammonium-platinum-chloride 

 obtained. 



The hydrogen given oif on solution of the substance in sulphuric acid was 

 measured. 



The iron was determined by ignition and weighing as oxide, and by solution 

 in sulphuric acid and titration with permanganate. 



As will be seen from the results obtained, the nitride prepared as above has a 

 composition corresponding to the formula Fe.^N. On solution in hydrochloric acid 

 the following reaction takes place : — 



Fe^N + 5HC1 = 2FeCl3 + NH.Cl + H. 



Found Calculated for FegN. 



N . , . 11-07 1111 



Te . . . 88-46 (mean of two titrations) . 88-89 



88-43 (by ignition) 

 H . . . 231 CO. from -275 subst. . . 24-4 c.c 



In another sample 10-94 N. was found. In a third case, in which the iron, after 

 solution of the nitride in acid, was precipitated by ammonia and weighed as oxide, 

 89-44 per cent, of iron was obtained and 10-5 per cent, of nitrogen, showing again 

 that the substance dissolves in acid according to the above equation, all the nitro- 

 gen being converted into ammonia. 



No percentages of nitrogen above 11-1 could be obtained, while any percentage 

 below that could be got according to the time during which the iron had been 

 exposed to the current of ammonia. 



These results are fully in agreement with those obtained by Stahlschmidt, and 

 confirm his conclusion that only one nitride of iron exists, and that it has the above 

 composition. 



Nitride of iron is formed when iron amalgam is heated in ammonia, and also 

 when ferrous chloride or bromide is heated in this gas. These methods, however, 

 do not so readily give a product containing the full percentage of nitrogen, and free 

 from the presence of a third element. 



Nitride of iron is a grey powder, rather less blue in tone than iron reduced from 



