44 
Explanatory Reports on 
[January, 
dense and tough structure. They shrink nearly 50 per cent of 
their bulk in burning, and thus acquire great density and hardness. 
The results have varied with the progress of the experiments 
conducted for the purpose of battling with the difficulties as they 
presented themselves. The following are the latest, as stated in 
a letter I have just received from Mr. Thomas : — 
1. “ That phosphorus replaces silicon as a heat-giving element 
with perfect success ; thus we have blown at least a 
thousand tons with under 1 per cent silicon, and much 
prefer it. We have often much under 0-5 per cent.” 
In explanation of this I may add that it has hitherto been 
found desirable to use for Bessemer purposes pig-iron containing 
exceptionally large proportions of silicon or carbon, or both. 
2. “ That up to 3 per cent phosphorus can be reduced to 
0*05 per cent (if the silicon is low) with regularity.” 
3. “ That when sulphur in pig is over 0*2 per cent, at least 
50 per cent is eliminated, often 75 per cent. When 
under o*i per cent there seems a difficulty, at present, 
in reducing to under 0*05 with regularity, though we 
often remove 80 per cent.” 
4. “ That the phosphorus is removed as phosphate of lime.” 
5. “ That the combustion of phosphorus provides not only 
sufficient heat to keep the bath liquid, but enough to 
keep the slag (formed by the 10 to 20 per cent addition 
of lime) also quite fluid. This slag contains — 
Lime and magnesia ... 50 to 65 per cent. 
Phosphoric acid 10 to 16 „ 
Silicic acid 6 to 16 
The rest oxides of iron and manganese.” 
6. “ We shall be able to run the vessels hard without material 
repairs for at least a week.” 
7. “ That the bricks can be produced regularly and easily, 
attention being had to the composition (the burnt brick 
should contain about 80 to 85 per cent of magnesia and 
lime, and 15 to 20 of alumina, silica, and oxide of iron), 
and the firing at a heat much superior to that even for 
silica bricks.” 
Mr. Thomas estimates the cost of lining at not more than 
is. 6d. to 2s. per ton of steel “ at worst.” 
I venture to suggest that there still remains open an apparently 
unexplored field for the application of this process, viz., the pro- 
duction of high quality tool steel from the best haematite pigs, 
as well as producing common rail steel from Cleveland pigs, 
by the Bessemer process, instead of the costly cementation of 
Swedish charcoal iron, and its subsequent fusion in crucibles. 
I am fully aware of the great difficulty of this problem, owing to 
the stubbornness with which the last traces of phosphorus and 
sulphur adhere. (2.) 
