368 Oh th: Alloys of Steel. 



pitate with tincture of galis. The portion in tlie retort bein^ 

 then poured out, the insoluble part is to be v>' aslied in repeated 

 portions of water, and then being first shghtly acted on by 

 muriatic acid to remove the iron, is to be treated with nitro- 

 mariatic acid, which will give a muriate of iridium. 



In these analyses, an experie;:ced eye will frequently per- 

 ceive, on the first action of the acid, the presence of the alloy- 

 ing metal. When this is platina, gold, or silver, a film of the 

 metal is quickly formed on the surface of the acid. 



Of alloys of platina, palladium, rhodium, and iridium and 

 osmium, a ready test is oirered when the point is not to ascer- 

 tain what the metal is, but merely whether it be }:)resent or 

 not. For this purpose we have only to compare the action 

 of tlie same acid on the alloy and on a jiiece of steel; the in- 

 creased action on the alloy immediately indicates the presence 

 of the metal ; and by the difference of action, which on ex- 

 perience is fcr.nd to be produced with the different metals, a 

 judgement may ba formed even of the particular one present. 



The order in which the different alloys stand with regard 

 to tliis action, is as follows : steel, chromium alloy, silver alloy, 

 gold alloy, nickel alloy, rhodium alloy, iridium and osmium 

 alloy, palladium alio}', platina alloy. With similar acid the 

 action on the pure steel was scarcely perceptible ; the silver 

 alloy gave A'ery little gas, nor was tlie gold mnch acted on. 

 All the others gave gas copiously, but the platina alloy in most 

 abundance. 



In connection with the analysis of these alloys, there arc 

 some very interesting facts to be obi-erved during the action 

 of acids on them, and perhaps none cf thcje are more strikuig 

 than those last referred to. Whei:i the alloys are immersed 

 in diluted acid, the peculiar properties which some of them 

 exhibit, not ox\\y mark and distinguish them from common 

 steel, and from each other, but also give rise to some consi- 

 derations on the state of particles of matter of different kinds 

 when in intimate mixture or in combination, which may lead 

 to clearer and more peri'ect ideas on this subject. 



If two pieces, one of steel, and one steel alloyed with pla- 

 tina, be immer:icd in weak sulphuric acid, the alloy will be 

 immediately acted on wilh great rapidity and the evolution of 

 much gas, and will shortly be dissolved, whilst the steel will 

 be scarcely at all affected. In this case, it is hardly possible 

 to compare the strength of the two actions. If the gas be col- 

 lected from the alloy and from the steel for equal intervals of 

 tune, the first portions will surpass the second some hundreds 

 of times. 



A very small quantity of platina allovcd with steel confers 



tliis 



