PreduUm of Steel frm Soft Iron ly the Diamond. 353 



At the end of feveral days fmall groups af cryftals were feparated, compofed of fmall flat 

 tetrahedral prifms, moft of them joined two and two, in the form of St. Andrew's crofs. , 

 Others were joined, to the number of three or more, in the form of a crofs. 



They were very foluble in water. When decompofed by ammoniac, the precipitate ap- ■ 

 peared of a light brown, becaufe contaminated by a fmall portion of oxide of iron. This 

 being diflblved in the fulphuric acid, and the new combination concentrated, the cryftals of 

 alum were firft feparated ; after which the liquor afforded only cryftals of magnefia, in tetralie- 

 dral prifms. 



This cryftallization of the muriate of magnefia containing alumine appeared to me to be 

 very remarkable. 



VII. 



Verbal Procefs of the Converjion of Soft Iron Into Cafl-fteel-, ly Means of the Diamond. By 



Citizen Guyton.* 



HE clafs may recoUeft the account f I gave of the great experiment of the combuftion 

 of the diamond in oxygen gas, in the focus of the lens of Tfirhhaufen, and the new truths I 

 have deduced refpedting the true nature of the diamond; of plumbago, which is its oxide in 

 the firft degree ; of charcoal, which is its oxide in the fecond degree ; and of carbonic acid, 

 which Is the produdl of its complete oxigenation. Thefe experiments gave our brother the 

 citizen Clouet the idea of feeking a new kind of additional proof, by attempting to caufe foft 

 iron to pafs to the ftate of fteel, by cementation with the diamond. 



It has hitherto been confidered as a decided fa£l, that iron does not melt but in its tran- 

 fition to the ftate of fteel, or caft-iron ; but in what ftate does the carbone enter into this 

 combination? It may be conjectured that it is in the ftate of plumbago, or oxide of the firft 

 degree ; becaufe that which is feparated by acids is found to poflefs the brilliant black colour, 

 and incombuftibility, which form its principal character. Hence it appeared proper to con- 

 clude that the carbone entered into this union in the ftate of oxidule ; and confequently that 

 the charcoal employed in the cementation of fteel began by parting with a certain portion 

 of its oxigen. Of this there was alfo an indication of confiderable ftrength in the charcoal 

 which had been ufed for this operation: as in hSt it has a more brilliant afpeft, and refifts 

 incineration nearly in the fame manner as charcoal in the mafs after ftrong ignition in clofe 

 ▼effels. 



* Read at the fitting of the National Inftitute of France, 26 Thermidor, in the year VII. and inferted ia 

 the Annals de Chimie, XXXI. 328. whence the prefent traDflation is made. 

 + Philof. Journal, III. 298. 



But 



