i88o.J 
New Scientific Processes and Inventions. 
43 
take uo this phosphoric acid immediately it is formed, and thereby 
produce a compound not decomposable by the hot iron, nor 
capable of combining with it, the original phosphorus may be 
Se Th 7 s te ?s the aim of the process of Messrs. Thomas and Gil- 
christ Some years ago I propounded a theory of the adhon of 
pudd ing in which the removal of the sulphur and phosphorus 
was attributed to a washing out by the slag or cinder, but at that 
time I merely regarded the aCtion as a sort of diffusion by ad- 
hesion like the diffusion of the impurities of dirty clothes in the 
water ’of the washing-tub. Following up this analogy, I ma^y 
say that the Thomas and Gilchrist process consists in what is 
equivalent to the addition of soda by the laundress ; a basic slag 
is produced which is capable of combining with the phosphoric 
acid and the sulphurous or sulphuric acid as 
of forming a phosphate, or a sulphur salt, that the iron cannot 
C °This 1 dea of°a basic slag is simple enough in theory, but diffi- 
cult to carry out in praaice. The very high temperature of ' the 
contents o 7 the Bessemer converter demands a highly refractory 
Unffig The ganisters, &c„ commonly used are siliceous -^., 
• A than basic — and lime, which is cheap, and has the 
acid rather th ^ if s i mp l y added in the ordinary con- 
combTnes wTth the silica o^he lining, and. forms a fusible 
limp cr’lass resulting in the destruftion of the lining and also of 
Ih” b£c ener U gies°of the lime. Soda is still worse, and other 
Ipciq attacked and go to supply material for the sla b or cinaer, 
Ihe first is the better devicefand accordingly the produ.ft.on of a 
lining that is at the same time basic and refradtory has been the 
obiel of a long struggle, following the first experiments which 
satisfied Mr. Thomas that a basic slag is capable of removing 
bricks is found to be 87 to 91 per cent carbonate is of hr ne ai ad 
magnesia * r «? to 6*5 per cent alumina ; and 3 to b 5 per cent 01 
magnesia , 35 0 r ’ 0 f no t less than 30 per cent of 
