An Attempt to analyse Cast Iron. 243 



GG. The muscles of the scuta consisting of two sets 

 which decussate each other. 



Plate VII. Fig. 2. 

 Represents two vertebrai and portions of ribs of the large 

 boa, to show their articulating surtaces. 



a a. The process peculiar to the vertebra of the boa. 



XLV. An Attempt to analyse Cast Iron. By Prbfessor 



Bi.RZELIUS*. 



It has for a long time been supposed that the principal 

 difference between cast iron and steel consisted in a 

 small quantity of oxygen being present in the former; 

 so that cast iron would be a kind of carburetted oxide of 

 iron, whilst steel, on the other hand, would be a carburetted 

 metallic iron. This pretty generally adopied conjecture re- 

 speciins the presence ot oxygen m cast iron, probably de- 

 rived from a comparison of the difference in malleability 

 of the cast iron and the steel, will on a closer examination 

 be found to contradict our experience respec'.ing the affinity 

 of iron and carbon for oxvgen ; for at the temperanire at 

 which cast iron is formed the carbon and oxygen ought to 

 be changed into gaseous carbonic acid. That cast iroa 

 should be an oxidule, is also contrary to analogy drawn 

 from other metallic protoxides, among which, as far as I 

 know, the lowest degree of oxidation is always that which 

 best will dissolve in acids, and which with the greatest 

 affinity will maintain this union ; but the cast iron exhibits 

 all the properties of a fully reduced metal. This question 

 respecting the composition of cast iron is of importance 

 to theory ; and its elucidation may prove useful when ap- 

 plied to the manufacturing of cast iron; but what particu- 

 larly deserves attention is the different states in which cast 

 iron can occur, together with the influence that these dif- 

 ferent stales may have on the qualiiy of the wrought iron. 

 The greater part of those differences in cast iron originate 

 indisputably from the different quantities of carbon dis- 

 solved by the iron in the smelting, by which an infinite 

 variety can be produced from the greatest to the least car- 

 buretted. A quicker or slower cooling contributes also 

 considerably to alter the colour and hardness of the cast 

 iron, though otherwise of identical composition. But 



• From Afhandlinzar i Fysik, Kcmi ocli Miner alngi, ulgi/ne tfJV.Hitiiiger 

 tch F. Uauliua. 3 H. Stockholm. 1810. 



O 3 these 



