2 56 Mr. Stodart and Mr . Faraday 
ther, when the forged piece was examined, by dissecting it 
with diluted sulphuric acid, threads or fibres of silver were 
seen mixed with the steel, having something of the appear- 
ance of steel and platina when united by welding : but when 
the proportion of silver was only part, neither dew, glo- 
bules, nor fibres appeared, the metals being in a state of per- 
fect chemical combination, and the silver could only be 
detected by a delicate chemical test. 
With platina and rhodium, steel combines in every pro- 
portion ; and this appears also to be the case with iridium and 
osmium : from 1 to 80 per cent, of platina was perfectly com- 
bined with steel, in buttons of from 500 to 2000 grains. With 
rhodium, from 1 to 50 per cent, was successfully used. 
Equal parts by weight of steel and rhodium gave a button, 
which, when polished, exhibited a surface of the most exqui- 
site beauty : the colour of tins specimen is the finest imagi- 
nable for a metallic mirror, nor does it tarnish by long 
exposure to the atmosphere : the specific gravity of this beau- 
tiful compound is 9.176. The same proportion of steel and 
platina gave a good button, but a surface highly crystalline 
renders it altogether unfit for a mirror. In the laboratory 
we ascertained that, with the exception of silver, the best 
proportion of the alloying metal, when the object in view 
was the improvement of edge tools, was about part, and 
in this proportion they have been used in the large way. It 
may be right to notice, that in fusing the metals in the labo- 
ratory no flux whatever was used, nor did the use of any 
ever appear to be required. 
Silver being comparatively of little value with some of the 
alloying metals, we were disposed to make trial with it as 
the first experiment in the large way 81 bs. of very good 
