360 
Mr Stodai't and Mr Faraday 
When any of these residua are boiled in diluted sulphuric or 
muriatic acid, protoxide of iron is dissolved, and a black powder 
remains unalterable by the farther action of the acid. It is ap- 
parently in greater quantity from the alloys than from pure steel, 
and when washed, dried, and heated to 300° or 400° in the air, 
burns like pyrophorus, with much fume ; or if lighted, burns 
like bitumen, -and with a bright flame: the residuum is protox- 
ide of iron, and the alloying metal. Hence, during the action 
of the acid on the steel, a portion of hydrogen enters into com- 
bination with part of the metal and the charcoal, and forms an 
inflammable compound not acted upon by the acid. 
Some striking effects are produced by the action of nitric acid 
on these powders. If that from pure steel be taken, it is entire- 
ly dissolved ; and such is also the case if the powder be taken 
from an alloy, the metal of which is soluble in nitric acid ; but 
if the powder is from an alloy, the metal of which is not soluble 
in nitric acid, then a black residuum is left not touched by the 
acid; and which, when washed and carefully dried, is found, 
when heated, to be deflagrating ; and with some of tlie metals, 
when carefully prepared, strongly explosive. 
The fulminating preparation obtained from the platina alloy, 
when dissolved in nitro-muriatic acid, gave a solution contain- 
ing much platina, and very little iron. When a little of it was 
wrapped in foil and heated, it exploded with much force, tear- 
ing open the foil, and evolving a faint light. When dropped on 
the surface of heated mercury, it exploded readily at 400° of 
Fahrenheit, but with difficulty at 370°. When its temperature 
was raised slowly, it did not explode, but was decomposed quiet- 
ly. When detonated in the bottom of a hot glass tube, much 
water and fume were given off, and the residuum collected was 
metallic platina, with a very little iron and charcoal. We are un- 
certain how far this preparation resembles the fulminating platina- 
of Mr Edmund Davy. 
In these alloys of steel the differences of specific gravity are 
not great, and may, probably, be in part referred to the denser 
state of the metals from more or less hammering ; at the same 
time it may be observed, that they are nearly in the order of the 
specific gravities of the respective alloying metals. 
