Dr Colquhoun on the Argillaceous Ore of Iron- 89 



This coal, treated in a similar manner with that which was 

 first analyzed, was found to yield 55.80 per cent, of coke. 



Three specimens of cherry coal, obtained from different beds, 

 afforded respectively 0.79, 1.87, and 1.66 per cent, of earthy 

 residue ; and 50.76, 52.16, and 52.93 per cent, of coke. The 

 residue from the first was white-coloured, with a pale reddish 

 yellow shade; in the second and third, the red colour was more 

 distinct. They consisted, respectively, in 100 parts, of 



100 100 100 



The first of these specimens possessed in perfection all the 

 external characters of cherry coal : and the last two, although 

 of a more friable composition than usual, differed in no other 

 respect from ordinary cherry coal ; agreeing with it perfectly, 

 both in their external appearance, and also in the nature of 

 the coke into which they were converted by calcination. 



These were the results of some analyses of the earthy mat- 

 ter contained in various specimens of the splint and cherry 

 coals. In regard to the latter, as the amount of its earthy 

 constituent appeared to be very decidedly less than had been 

 found either in the experiments of Mr Mushet or of Dr Thom- 

 son, the former of whom states it at 1.75', * and on another 

 occasion at 4.05' -f* per cent., and the latter at 10 per cent., \ 

 a difierent analytical process was resorted to, in order to put 

 the results above stated to the test. The former method had 

 consisted in reducing the coal to a very fine powder, and then 

 igniting it in a platinum capsule placed over a spirit lamp, 

 until it was reduced to a white ash. The new method was 

 by taking a determinate quantity of the same coal, and defla- 



♦ Philosophical Magazine^ iii. 13. t Ibid, xxxii. 313. 

 + Annals of Philosophy, xiv. 81. 



