24? Mr. D. Mushet on the 0]i/siaUizaiion of Cast Iron, 



nally composed. In breaking up the lower part of the cindery 

 mass, the cubical crystals of iron were first discovered ; their 

 colours were green, gold, and coppery ; the largest cube did 

 not exceed one-tenth of an inch on the base, and many were not 

 one-fourth part of this size. 1 collected in all forty or fifty 

 pounds of the best; and several hundred weight, containing what 

 I should now reckon superb specimens, were tlirown away. 



In riftuig the salamander with wedges, one of the jomts of 

 the stone- work was discovered to contain a flexible white sub- 

 stance, like amianthus, lining it on both sides. This sub- 

 stance had a curious metallic taste, and grit between the teeth. 

 By endeavouring to split the stone in the dii'ection of the jomt, 

 in order to obtaui as much of this substance as possible (which, 

 as it filled the joint undisturbed, had a regular fibrous cry- 

 stallization), I fbmid it open into a regular fissure, filled with 

 compact iron crystallized in imperfect cubes. The density 

 and fracture of this mass, about two inches thick, resembled 

 galena. It seemed composed of an infinite number of small 

 cubes, the superficies of which were easily discerned in its 

 highly-polished fracture. Specimens of this sort are not un- 

 commonly found in breaking up old furnace-hearths ; but I do 

 not recollect having met with the copper-coloured crystallized 

 iron, except in the instance above mentioned, though the ami- 

 anthus and the massive cubical iron I have fi'equently seen. 



The high temperature in which the gold- and copper-co- 

 loured crystals were ibrmed, and their attachment to a metallic 

 base, induced me at first to conclude they were purely metallic. 

 Like the mass found in the fissure, they bruised in a mortar, 

 and were equally magnetic. Several of the crystals in suc- 

 cession were exposed to the action of the blow-pipe at a bright 

 red heat ; the gold colour deepened to a green, followed by a 

 blue ; and then successively passing through the usual shades, 

 returning always the tinge of the original ground, hke the 

 copper colour in fine indigo. When exposed to the action of 

 the blow-pipe on charcoal, the crystals seemed to burn, and 

 emit greenish scmtillations with borax ; they remained for a 

 great length of time, without losing either colour or form. 



I am, yours, &c. D. Mushet. 



Coleford, Gloucestershire, Jan. 0, 1823. 



As tlie paper before alluded to contains a particular detail 

 of the various stages of the crystallization of cast iron, and 

 of the method of obtaining it ui the large way, it is my inten- 

 tion to forward to you, for the Magazine, a copy of the same, 

 leaving it for you to determine, whether, in the absence of en- 

 gravings, it is calculated to convey information to your readers. 



VIII. On 



