169 



On the Alloys of Steel. By J. Stodart, Esq. F.R.S. and Mr. M. 

 Faraday, Chemical Assistant in the Royal Institution. Communi- 

 cated by J. Stodart, Esq. F.R.S. Read March 21 , 1822. [Phil. 

 Trans. 1822, p. 253.] 



The metals which form the most valuable alloys with steel, for the 

 purpose of manufacture into cutting instruments, are silver, platinum, 

 rhodium, iridium, osmium, and palladium. Eight pounds of Indian 

 steel, alloyed with -j-J-o-th of pure silver, formed a very hard and 

 tenacious compound, well adapted to the manufacture of cutlery and 

 several edge tools. Ten pounds of the same steel with T -ihrth of 

 pure platinum, produced an alloy less hard but more tough than the 

 former. 



With rhodium, iridium, and osmium the alloys were also excellent; 

 but the scarcity of those metals prevents their general introduction 

 into the manufactory. 



The authors then state the processes of analysis which they 

 adopted to assure themselves of the composition and perfection of 

 the respective alloys. 



The alloy with platinum is rapidly acted upon by sulphuric acid ; 

 and to ascertain the presence of the platinum, the residuary black 

 powder of this solution, after having been heated red hot, is to be 

 treated with nitro-muriatic acid, and the platinum reduced by heat. 



The residuary matter of the alloy of silver, when similarly acted 

 on by dilute sulphuric acid, was dissolved in nitric acid, and tested 

 by muriatic. The residue of the alloy of palladium having been 

 heated, was dissolved in nitro-muriatic acid, and precipitated by 

 prussiate of mercury. From the rhodium residuum the iron was re- 

 moved by muriatic acid, and long digestion in nitro-muriatic acid 

 gave an easily distinguishable muriate of rhodium. The residue of 

 iridium and osmium was decomposed in the usual way by the action 

 of caustic soda. 



The rapid action of .dilute sulphuric acid upon these alloys, as 

 compared with pure steel, is next adverted to, and is referred to 

 electrical action, a voltaic combination being produced by the libe- 

 ration of the difficultly oxidable metal. 



The black insoluble residue of these alloys, obtained by the action 

 of dilute sulphuric, appear to be peculiar compounds. When boiled 

 in dilute muriatic acid, protoxide of iron is dissolved, and a black in- 

 soluble compound remains, which, when dried and heated to 400, 

 burns like pyrophorus, leaving protoxide of iron and the alloying 

 metal : hence, say the authors, during the action of the acids on the 

 steel, a portion of hydrogen enters into combination with part of the 

 metal and charcoal, and forms an inflammable compound not acted 

 on by the acids. The action of nitric acid on some of these residua 

 produces a deflagrating compound, especially that from the alloy of 

 platinum. 



This paper concludes with some observations on the probable im- 



