Cast Iron, Steely and Malleable Iron. 47 



those specimens, in three different glasses, hydrochloric acid. 

 No. 1. was attacked very violently: the liquid became milky, 

 and a yellow precipitate with a very few traces of black flocks 

 remained. During a space of nine weeks the solution had im- 

 bibed so much water from the surrounding atmosphere, that 

 the glasses were nearly overflowing. The acid was then 

 poured off and distilled water poured over the precipitate ; tiie 

 precipitate was now white and flocky, and the most copious 

 of the three samples. 



No. 2. was not so violently attacked, and did not become 

 milky: first, fine black scales became separated, adhering to 

 the sides of the glass very regularly; afterwards, the interstices 

 between these black scales or spots became filled up with the 

 before-mentioned yellow powder. The whitish powder ap- 

 peared very fine, never granulated or flocky, and adhered to 

 the sides of the glass almost entirely. The whitish precipitate 

 of Nos. 1. and 3. fell to the bottom of the glass. 



No. 3. was the most rapidly attacked by the acid, and 

 became milky, the same as No. 1. The liquid was, after a 

 lapse of nine weeks, rather turbid and showed the smallest 

 quantity of black scales swimming in the liquid. A few hours 

 after the acid had been poured over it, it became turbid and 

 very yellow, which showed that it had combined the quickest 

 with the oxygen of the atmosphere. 



The day after the acid had been poured on No. 2. the sur- 

 face only began to acquire a yellow colour. In No. 3. the 

 black flocks seemed entirely to have disappeared, and the yel- 

 lowish powder ascended in part to the surface, and the remain- 

 der fell to the bottom. The difference therefore between the 

 granulated exterior of the same bar, and the interior crystal- 

 lization, seems to consist in this, that the exterior produces less 

 white powder in a very divided state and more carbonaceous 

 scales, or that the granulated parts, be they inside or outside 

 of the bar, contain less of the white powder and more black 

 scales than the crystallized ; I therefore infer, that the carbon 

 is here substituted for silicon ; and as No. 3. contained more 

 silicon than No. 2., it seems either that the silicon of No. 2. 

 was partially driven away during its preparation by the carbon, 

 or rather that the silicon remained in combination with carbon, 



A fragment of Bombay wootz was also vei'y slowly attack- 

 ed by the acids, and deposited on the sides of the glass the 

 before-mentioned white powder. 



21'71 grains of No. 3. left white residuum dried at the heat 

 of boiling water = 0*3437 grains. 



A part of a coloured blister of Dannemora steel deposited 

 likewise a n^liite 'pox^der^ and was like the before-mentioned 

 samples. 



