194 On Tribasic Phosphoric Acid. 



of phosphoric acid in the iron ore proper will enter into the 

 maas of metallic iron by the process of redaction and smelting, 

 and, in combination with other constituents, give it its distinc- 

 tive character. This small percentage o\' phosphorus in metal- 

 lic in»n I hold to be necessary to make a good article 

 and I do not doubt that the absence of it, as in the ease of 

 iron made from Bome magnetic and titanic ores, will be sup- 

 plied by Bome other Bubstance, say Biilphur or carbon. 



A difference in the relative proportions of carbon, sulphur, 

 an«l phosphorus, will change the properties of the metal in Bnch a 

 way as to render it more or less adapted to certain particular 

 uses. As, however, very few exaet analyses of metallic iron 

 exist we have first to ascertain those proportions of earbon, 

 sulphur, and phosphorus, and their relations to the changes 

 they effect in the properties of pure iron, before we are able to 

 produce an iron of a certain character by the mixing of dif- 

 ferent ores, the composition of which we know. 



We have also to make a distinction between the phosphoric 

 acid in tin- ore proper, and the phosphoric acid in the gangue. 

 This latter I believe to he comparatively easy to eliminate and 

 bring completely into the slag. The proof of this, as also the 

 results of an attempt to remove an excess of phosphoric acid, 

 t ] ia , i, x gome peculiarity of composition or form may have 

 entered into com hi nation with the ore proper, will he the subject 

 ,,j another aeries of experiments. 



For ih<- investigation of Bome of these methods I'm- the 

 separation of phosphoric acid from alumina, a precipitate 

 similarly prepared and similarly treated was used, which, how- 

 nol a- well washed out a- the iron precipitate had 

 I ,,.,.,, ii bad tlm same composition as the iron com pound, with 

 the exception of the water, of which it contained a little more. 

 Ai. <> I. • PO 5, hHO 58 (Al, 0,=51.5). 



PO, 32.78 



Al, O,=19.02 



IK) =48.20 



