1 22 MR. F. C. CALVERT AND MR. R. JOHNSON ON THE 



These details of analysis appear to us the more important 

 when it is remembered that most of the heterogeneous sub- 

 stances existing in pig iron, are present only in minute 

 quantities, and that it is on their gradual removal or decrease 

 that the subsequent quality of the wrought iron depends. Also, 

 it is necessary to bear in mind, that we had to trust entirely to 

 the exactitude of the analytical methods adopted to appreciate 

 the chemical changes which gradually took place in the melted 

 mass during the hour and a quarter that the conversion of the 

 cast into wrought iron lasted. 



Iron. 



The quantity of iron was determined by dissolving one 

 gramme of iron in pure hydrochloric acid, reducing the 

 solution to a perfect protosalt by a little pure zinc, and then 

 determining the amount of iron by Margueritte's process. 



Carbon. 

 To determine this element we found, after many trials, 

 that the best process was to reduce the iron into very fine 

 powder, either by pulverization or by means of a file, and 

 then to burn the carbon under the influence of a red heat 

 by a slow current of pure and dry oxygen gas. The appa- 

 ratus which we used was the following: — 



