428 On the Presence of Phosphorus in Pig-iron. 



XL XTI. 



Silicic acid .... 41-11 37-84 



Alumina 13-45 13-20 



Lime 29'82 20-68 



Magnesia 4-75 2-93 



Protoxide of iron . . 6-44 20-83 



Protoxide of manganese . 0-66 0-80 



Alkalies . . . = . 1-84 1-08 



Sulphide of calcium . . 1-34 0-87 



Phosphoric acid . . . 0-15 1-77 



Loss 0-44 0-05 



10000 100-00 



No. XL is that of a slag resembling black bottle-glass in ap- 

 pearance^ and from its liquidity when melted is termed by the 

 workmen a scourincj slag. It was from argillaceous ore. 



No. XII. from pisolitic ore when the working of the furnace 

 was much deranged. This slag was exceedingly heavy, of a pitch- 

 black colour, \vith the surface of the blocks in the tap ivagons of 

 the dull, dark red, bronze-like aspect characteristic of very bad 

 furnace slags. 



From these results we must regard the oi'e as being melted up 

 (not smelted) and flowing away with the slags, although in vei-y 

 different degrees in the two examples given. 



The analyses of crystalline slags by Percy and D. Forbes*, in 

 all of which phosphoric acid was sought, lead to the same infer- 

 ence, phosphoric acid having been discovered and estimated in 

 only one instance, and that in a slag similar to XI. It contained 

 FeO 4-94, and PO^ 019. 



In conclusion we will briefly recapitulate the results of our 

 experiments. 



Jst. That in assaying ores, all the phosphorus of the phos- 

 phates will be found in the button. 



2nd. That when the ordinary iron ores, such as the argilla- 

 ceous ores, black bands, hsematites, &c. are smelted, the iron 

 produced, if it be gray, will contain all the phosphorus of the ore, 

 whether the furnace be driven with hot or cold blast. 



Lastly. That the slag may contain phosphoric acid in deter- 

 minable quantity when white iron is being smelted. 



* British Association Report, 1846; and Chem. Gaz. vol. v. p. 29. 



