Miscellaneous Intelligence. 433 
familiar vena aed “ process itecle was then ce de- 
This iron is melted in a cupola furnace, run converter— 
a charge beans 12,000 pounds—and the blast turned on. “The first 
change is in the oxydation of iron and silicon. The silicon be- 
comes silioia acid and enough of the iron oxydizes to satisfy the 
affinities of the acid and does not decompose during the remain- 
carbon,—that is, as compared with that derived from the silicon. 
* * * ‘The heat generated by the — burning to silicic acid 
will be found by the application of the coefficients and formule 
of the mechanical theory of heat, to be oad two and one-half to 
three times greater than that generated by the burning of the 
carbon to carbonic oxyd. Another circumstance of importance is 
that the silicic acid remains as a dense fluid in the converter, no 
part of its heat being lost, ex 20 thes as is carried out of the 
a- 
tent by converting it cers ae le the carbon i is vaporized, a 
physio! change Sa much heat, and the vapor thus formed 
is carried the converter at a very high temperature. Hence 
will be seen the necessity of employing irons containing high per- 
centages of silicon. At least two per cent of this element is essen- 
be any less quantity being BS OR t to generate heat enough 
pooh: process. It is often assert aa that irons for Bessemer con- 
version must be ‘gray irons,’ as they are called; i. e., irons rich in 
carbon. Now, although this happens as a rule, to e true eno ugh, 
it is apt to lead to misapprehension. The fact that Bessemer pig 
irons are carbonized varieties is an accident, and n 
t What is essential is that it should ni ; large quan- 
tity of silicon, and very little—indeed, the least possible—of sul- 
tain a high percentage of carbon, as all smelters are aware, is 
fact is a feature of the blast-furnace, and almost without excep- 
tion. If an iron . could be ep with much silicon, a little car- 
