CHEMICAL SCIENCE. 179 



fered, but also with almost identical processes. Moreover, certain 

 kinds of steel, and it seems particularly those obtained by puddling, 

 after undergoing many energetic fagotings, appear to be susceptible 

 of losing their characteristic properties of hardness and elasticity 

 acquired by tempering, and to acquire a considerable resemblance to 

 the most ductile irons. Lastly, the cast steels produced by the new 

 processes of fabrication, when properly forged, possessed an elastic 

 resistance capable of undergoing a much greater strain than those 

 manufactured by the ordinary methods. 



M. Chevreul then made the following observations respecting black 

 cast iron and the composition of steels : 



1. Black Cast Iron. At the end of the last century, Proust ob- 

 served that black cast iron, when heated with weak sulphuric acid, 

 yielded an oily matter, a portion of which was carried off by the 

 hydrogen gas, and made the tubes of the apparatus greasy, while the 

 other portion remained mixed with the black residue, from which 

 alcohol could extract it. I never neglect an opportunity of quoting 

 this observation as an example of the possibility of producing, by 

 chemical forces, compounds analogous to those of organic nature. 

 Experience has long since proved that aqueous vapor, by reacting on 

 charcoal, yields, besides carbonic acid, or oxide of carbon, nothing 

 but hydrogen, and not carburetted hydrogen, as hitherto believed. 

 The combination of the cast steel with the nascent hvdrogen seeming 



** O 



to me difficult to admit, this has led me to conjecture that in Proust's 

 experiment the water might assist in the production of the oily mat- 

 ter simultaneously with the carbon and hydrogen. Now, M. Fremy's 

 observations seem to throw a light on the subject, by indicating that 

 it is not carbon, as was represented, which yields the oily matter. 



2. Composition of Steels. Independently altogether of science, 

 two bodies possessing different properties have never been con- 

 founded ; so that when an iron was observed which hardened on 

 being suddenly cooled, it was distinguished from one preserving 

 its original ductility after undergoing the same cooling influence. 

 Thenceforward, the name of steel was bestowed upon the first sub- 

 stance to distinguish it from what is properly called iron ; or, in other 

 words, between steel, which tempering hardens, and iron, which tem- 

 pering does not harden. Since the time of the revival of chemistry, 

 the difference between steel and iron was attributed to the presence 

 of about a thousandth part of carbon in the former. Later, the influ- 

 ence of various bodies on steel was recognized. Berthier mentions 

 chromium ; Faraday and Stodart, aluminium, platinum, and its ac- 

 companying metals ; but the fact which to me seems of the greatest 

 importance, is the method by which MM. Faraday and Stodart ob- 

 tained from cast iron some centiemes of iridium and osmium, which 

 when analyzed yielded no trace of carbon. Setting aside the ques- 

 tion whether steel is an indefinite compound of iron and one or sev- 

 eral simple bodies distributed through the whole mass of the steel, or 

 whether it is a definite compound of iron with one or several simple 

 bodies distributed in indefinite proportions in the iron in excess of 

 the elements of the definite compound, I conclude, from the whole of 

 the facts I have stated, that in a chemical treatise steel in general 

 must be regarded not as a definite compound by the nature of its 



