VOL. LXXXV.] PHILOSOPHICAL TRANSACTIONS. 585 



also made on steel wire with the same result, (e) A few drops of diluted 

 nitrous acid were applied to a piece of polished wootz, steel, and iron. The 

 parts of the wootz and steel so wetted became black, but the iron was made 

 brown. 



^ 6. Experiments with diluted sulphuric acid. — ^This acid liquor was made by 

 mixing I measure of concentrated sulphuric acid with 3 of pure water. Before 

 I felt any degree of confidence in these experiments with respect to the carbon, 

 and the proportions of hydrogen gaz from wootz and water, I repeated them 

 often ; but I here think it necessary to relate only one experiment. 



200 grs. of wootz, from the surface of which oxide, and any other extraneous 

 matter, had been carefully rubbed ofF, were put into a retort with 5 oz. measures 

 of diluted sulphuric acid. In the temperature of 55° of the room, in 24 hours, 

 about a pint measure of gaz came over into a jar filled with, and standing over, 

 lime-water; without any disturbance of its transparency, or diminution of the 

 bulk of the gaz. The liquid in the retort became green, and a quantity of 

 black wool-like sediment appeared on the undissolved wootz. 



On applying the lamp the dissolution went on rapidly, and black matter con- 

 tinued to be separated, and gaz to rise, till the whole of what seemed to be so- 

 luble in the menstruum disappeared. When about ^ths of the matter were 

 dissolved, a white sediment like the siderite of Bergman began to appear, and in- 

 creased as the dissolution went on. By standing, still more of this white sedi- 

 ment fell down, and green crystals, apparently those of sulfate of iron, formed 

 a stratum which lay over the white matter. The black matter adhered to the 

 sides of the retort, it appeared also on the surface of the liquid, and some of it 

 •was deposited under the white sediment. This experiment was made with steel 

 wire, and the toughest iron wire. 



The phenomena during the dissolution of steel were the same as those last 

 related; except such as obviously arose from mechanical differences in the sub- 

 stances to be dissolved. In particular the quantity of insoluble black matter, 

 of white sediment, and of green crystals, was apparently the same. But with 

 respect to the phenomena of the dissolution of iron, there was one material 

 difference between it and the dissolution of wootz and steel, namely, that the 

 liquor was not turbid and black, but clear, with a very small quantity of black 

 matter on its surface. It is however proper to state, that seemingly the same 

 kind and quantity of white sediment and green crystals were produced as from 

 the dissolution of wootz and steel. I think it of consequence also to notice, 

 that the black matter appears in the greatest quantity when about -l, or ^ths 

 of the matter is dissolved ; but after this period, though gaz be separated in as 

 great quantity as before, the black matter seems to diminish. Hence I was at 

 first inclined to conclude with Mr. Berthollet, that part of this black or carbo- 



VOL. XVII. ' 4 F 



