34. 



MR. E. W. BINNET? ON THE ACTION OF 



For the sake of comparison, it may be as vieW to give an 

 analysis of the Dowlais hot-blast iron, No. 4 : * — 



Suspended graphite 1"22 



Combined carbon 2' 13 



Phosphorus ., 0"21 



Manganese 0'17 



Alumina 000 



Sulphur 0-00 



Silica 1 -21 



Iron 9506 



100-00 



The average specific gravity of cast iron, according to 

 Karsten, is 7"5.f 



It will be at once evident that not only has a great altera- 

 tion taken place in the specific gravity of the specimen, but 

 that a large proportion of its iron has been removed, and its 

 place occupied by carbon and silica, for the bulk and shape 

 of the specimen still remain the same, although it has lost so 

 much of its weight. The iron appears dispersed through the 

 earthy mass in little globules of a bright colour, when viewed 

 under a lens. 



Nos. 2, 3, 4, and 5 are specimens of portions of other edge 

 wheels of cast iron. All of them shew a decomposition from 

 the outside to the inside, varying, in different cases, from a 

 third to half an inch, the middle part of the casting still 

 consisting of metallic iron, surrounded by a brownish black 

 substance resembling plumbago. In every respect as to size, 

 and the use to which they were applied, these specimens 

 are the same as No. 1, which, as before described, is altered 

 throughout its whole mass. Whether the iron varied from 

 the last-named specimen, or they were placed in a different 

 position, and thus subjected to other conditions, there is no 

 evidence to shew. 



* Mallet *s Report, Vol. xiii. Brit, Asa. Rep., p. 4. 

 t Vol. v., Gmelln'8 Hand Book of Chemistry, p. 211. 



