138 On the Affinities cj 



The following experiments, performed with arglllaceoii?, 

 siliceous, and calcareous ironstones in the state in which 

 thcv are taken from the mine, cxhil)it an exact coincidence 

 of eftcct with those artificially compounded. 

 \si. Argillaceous Ironstone. 

 Of this particular quality the mine presents three strata, 

 each about ^^ inches \\\ thickness. They arc found about " 

 2 feet incumbent to a regular stratum of shctUy limestone 

 about 9 inches thick, and containing a thin measure of cal- 

 careous ironstone in its very centre. The shale or matrix 

 in which the ariiillaceous strata are found, is a blackish Ijlue 

 clay in thin laminae, and of that particular quality best cal- 

 culated to stand the heat of a large furnace. Above this 

 shale is found a small gritted sandstone, commonly called 

 icater U'h'viy as hard as flint and about four feet thick. 



The colour of the ironstone resembles very much the ap- 

 pearance of the schistus described above, only a few shades 

 darker in point of colour. The fracture rough, and mi- 

 nutely granulated. Its hardness as an ironstone below 

 nediocnty. A solitary muscle-shell is sometimes detected 

 upon its surface; and on one piece I found an entire bivalve 

 neatly forced open, with the configurations distinct. It 

 may be proper to remark, that the measure of calcareous 

 matter below is an entire coagulation of muscles ; and 

 fiirlher, that the under surface of the roof, rock, or sand- 

 stone, formcrlv mentioned, next to the matrix, is beauti- 

 fully waved like the sea beach after flood tide. Irregu- 

 larly dispersed along this surface are also found convex fi- 

 gures of small pine-shoots very perfect and entire. The 

 matrix or shale below bearing the corresponding impres- 

 sion, with all the accuracy of a highly finished mould. 



The specific gravity of this ironstone was* 



Exp. I. 400 grains of raw ironstone were fused per se. 

 The result was a" dark coloured glass, the upper surface of 

 which was covered with a film of oxide of a lake colour. 

 Two small cavities were found formed, from which I in- 

 ferred that the first portions of metal would be revived with 

 a small dose of carbon. 



Exp. II. 400 grains of raw ironstone, 



5 of carbon, or l-80th. 



This mixture was reduced to a very beautiful shining 

 black glass with a metallic lustre. Under it was found a 

 very perfect spherule of iron which weighed exactly 8^7 

 crains, and equal in point of produce to 2i per cent. 



The surface of this glass was imperfectly radiated with 



* The author has omitted to fill up this blank. 



confiiiuratioua 



