584 PHILOSOPHICAL TRANSACTIONS. [aNNO 17Q5, 



melted. Nor is this result difficult to account for by those who consider the 

 different temperatures in different parts of the same fire; even supposing the in- 

 strument to invariably indicate the real temperature. 



(i) Equal weights, namely, 500 grs. of wootz, steel wire, and gray pig iron, 

 were exposed, for half an hour, in the same crucible well covered, to a pretty 

 considerable fire. On cooling, the pig iron was found to have been fused, but 

 the other 2 states of iron had retained their form. The pyrometer was con- 

 tracted to near the 1 40th degree. 



(k) I melted together 500 grs. of steel wire and 50 grs. of gray pig iron, in a 

 close vessel, without any addition of carbon. The steel so alloyed was more 

 brittle than cast steel. Its grain was coarser, and it had not the uniformity of 

 texture and colour of melted wootz (§ 3. h;) but had more resemblance to some 

 of the fractures of the unmelted wootz (§ 3. d.) 



^ 4. Effects of fire and oxygen gaz conjointly. — A piece of wootz ignited to 

 whiteness, being exposed to a blast of air in the charcoal fire of the forge, emit- 

 ted sparks like those of iron, and steel, in these circumstances. At the same 

 time it melted in the state of oxide of iron. 



^ 5. Experiments tvitli diluted nitrotis acid. — (a) 200 grs. of the substance 

 under examination were first digested, and afterwards boiled in 3 oz. measures of 

 concentrated nitrous acid mixed with an equal bulk of water. A dissolution 

 took place, with a discharge of nitrous gaz. The mixture, reduced by boiling 

 to half its bulk, was diluted with water, and while boiling hot was filtrated 

 through paper. Excepting a few grains of black matter, the whole mixture 

 passed through the filtre. The filtrated liquor evaporated to dryness afforded 

 matter, which after being kept red hot for 2 hours was a light spongy reddish 

 substance; that weighed 270 grs. 



(b) 30 grs. of the reddish substance (§ 5. a) digested in ^oz. of concentra- 

 ted acetic acid, on filtration and evaporation to dryness yielded 1 -i- gr. of gray 

 matter, which was ascertained to be oxide of iron. 



(c) The blackish matter left on the filtre {^ 5. a) was repeatedly digested in 

 diluted nitrous acid. The filtrated liquors on evaporation afforded at first a few 

 grains of oxide of iron, and at last a very minute quantity. 



(d) 60grs. of the reddish matter (^ 5. a) with a bit of sugar, were digested 

 in diluted nitrous acid. The filtrated liquid on evaporation to dryness yielded a 

 few grains of a brownish substance, which after many experiments, was found 

 to be oxide of iron. Of these it will be satisfactory if I mention, that a little 

 of the brownish substance fused with the fluxes by the flame and blow-pipe, did 

 not afford a reddish or purple glass from the exterior or white flame; nor a co- 

 lourless one from the interior blue flame. The experiments (^ 5. a— d) were 



