Mr Dalton's System of Chemical Philosophy. 351 



gains about l-180th of its weight by being converted into steel.* But Mr 

 Mushet found that though steel gains weight upon the iron when copi- 

 ously imbedded in charcoal, yet it loses weight if the charcoal is only 1-90 

 or 1-100 of the weight of the iron, f The same ingenious gentleman seems 

 to estimate the carbon in cast steel, from synthetic experiments, to be 

 1-lOOth of its weight. 



" From analytic experiments, however, there does not appear reason to be- 

 lieve that steel contains so much, if any charcoal. Pure steel dissolved in 

 dilute sulphuric acid gives hydrogen gas containing no carbonic acid nor 

 oxide, neither is there any appreciable residuum of any kind in general. 



*' On considering all the circumstances, I am inclined to believe, that the 

 properties which distinguish steel from iron are rather owing to a peculiar 

 crystallization or arrangement of the ultimate particles of iron, than to 

 their combination with carbon or any other substance. In all cases where 

 steel is formed, the^ mass is brought into a liquid form, or nearly approach- 

 ing to it, — a circumstance which allows the particles to be subject to the law 

 of crystallization. We see that great change is made in steel by the mere 

 tempering of it, which cannot be ascribed to the loss or gain of any sub- 

 stance, but to some modification of the internal arrangement of its parti- 

 cles. Why then may not its differences from iron be ascribed to the same 

 cause?" Pp. 216,-218. 



In the addenda to the volume Mr Dalton says : '^ Since writing the ar- 

 ticle at page 214', I have had an opportunity of analyzing the crystalline 

 steel, formed by Mr Macintosh's process of cementation by means of coal, 

 gas. I dissolved twenty-one grains of this steel in sulphuric acid, with 

 only a very slight excess of acid. The whole was dissolved except about 

 one- tenth of a grain of silvery-like particles. The gas obtained amounted 

 to 29.6 cubic inches. It yielded no trace of carbonic acid. When fired' 

 with oxygen it yielded 3 per cent, upon the volume of hydrogen of carbo- 

 nic acid ,* and this arose, as I ascertained, from the hydrogen containing 3' 

 per cent, of carburetted hydrogen gas : it contained no carbonic oxide. 

 Supposing the carbon to have been combined with the iron, it would amount 

 only to about 5-8ths of a grain, to 100 grains of iron. Whether such a 

 quantity can be deemed an essential or an accidental ingredient of steel, 

 may be a subject of consideration." P. 354. 



To us it appears, that whether carbon should or should not turn out to 

 be essential to the manufacture of steel, the iron can never be said to be in 

 combination with carbon, in the same sense that it is said to be in combi- 

 nation with sulphur in its sulphurets. A difference in the structure of 

 iron and steel exists ; but such a difference does not imply necessarily a 

 chemical change ; as we know water to be chemically the same as ice, and* 

 as steam ; and as we know common sulphur, which is very brittle, to be 

 chemically the same as that of flexible sulphur, which is obtained by melting 

 common sulphur, raising it to a high temperature, and dropping it into cold 

 water. With regard to steel, the question is, whether carbon is essential 

 to its change in structure? or whether heat alone is adequate to this change ? 



* Manchester Mentoirs^ vol. v. p» 120* f Philos. Mag, vol. xiii. 



