2 Dr.ColquhounonanewFonnofCarho)u [July, 



form, especially of an important body, is obtained. This is in 

 fact to approximate the laboratory of the chemist to the great 

 officina of nature, where many a substance must exist in states 

 very different indeed from any wh;ch the industry of the experi- 

 menter has yet enabled him to discover, or his art to make it 

 assume. 



It is to several highly interesting states of aggregation of 

 carbon, one of which is not only of a very singular structure, but 

 also an entirely new form, that it is the object of this notice to 

 direct attention. 



This last-mentioned formation occurred in the new steelifying 

 process of Charles Macintosh, Esq. of Crossbasket. I had 

 undertaken, at the request of that gentleman, who is an eminent 

 practical chemist, to superintend, during his temporary absence, 

 a series of experiments intended to ascertain the best details of 

 practice and apparatus for his most ingenious process of the 

 conversion of iron into steel. The principle of his invention is 

 probably well known ere this to a great part of the men of 

 science, as well as to the mechanics of this country. It consists 

 in introducing into the contact of iron, ignited to nearly a white 

 heat in an air-tight earthen vessel, a current of a gas containing 

 caribou as one of its constituents, and which in practice is usually 

 carfc'iretted hydrogen gas. In this operation the gas undergoes 

 a partial decom{)osition, occasioned probably by various causes, 

 but principally by the influence of the high temperature to which ' 

 it is exposed, and by the mutual reaction which takes place in " 

 that temperature between it and certain other of those gaseous 

 bodies, such as carbonic oxide, with which it is always, to a 

 certain extent, intermixed. And the iron also, by virtue of its 

 own peculiar affinity for carbon, will undoubtedly co-operate 

 with the elevated temperature in rendering the disengagement 

 of that substance from the hydrogen more complete. 



The result of these decompositions is an abundant precipita- 

 tion of carbon. This carbon, as it has just before been in 

 chemical union with another body, exists of course in a state of 

 the most minute division at the moment of its precipitation ; 

 and it is probably owing greatly to this circumstance that its 

 particles are found to penetrate the iron more rapidly and more 

 equably, and to form a more intimate union with the whole mass 

 of it than was formerly practicable under the old method. 

 Besides, there is found to result the additional advantage of a 

 great saving of fuel on the system of Mr. Macintosh, because 

 nothinjj could be more difficult than to ignite iron thoroughly 

 when imbedded, as under the previous system, between two 

 masses of soHd charcoal, which is one of the very worst conduc- 

 tors of heat. When fresh gas continues to be introduced in 

 proportion as the previous supply is deprived of its carbon, the 

 process of precipitating the carbon in an impalpable powder. 



