C. G. T. MoRisoN 169 



long, as each was examined under a lens and those showing any adherent 

 impurity disregarded. 



It was decided to determine only phosphoric acid, calcium, and 

 silica. The result is given below : 



Phosphoric acid 26"30] 

 Calcium oxide 46'71 > 

 Silica 11-02 J 



These figures being in the ratio of one molecule of phosphoric acid, 

 one of silica, and between four and five of calcium oxide. 



The results of other analyses of the crystals which were not so pure 

 as the above are given below : 



I II III 



CaO 38-90 44-20 37-91 



P0O5 19-45 21-53 



SiO„ 10-06 10-94 9-36 



FeO 17-03 



The crystals could not be obtained pure in sufficient quantity to 

 make a complete analysis possible. 



The points brought out by the above are two: 1st the large amount 

 of iron the crystals contain, 2nd the constant molecular ratio of 1 : 5 

 between the calcium and the phosphoric acid. 



These analyses would rather point to a body of the general form 

 (MO)5MiO . SiO.2 . P2O5 where M is calcium more or less replaced by 

 ferrous iron, and Mj ferrous iron. 



These crystals are very soluble. They dissolve readily in carbon 

 dioxide solution, and of the total phosphoric acid present in this slag 

 93-2 7o is soluble in a solvent containing 1 "/o of citric acid, or one- 

 twentieth of the concentration usually employed. 



The percentage composition of such a body and the analytical 

 figures obtained from the pure crystals are given below : 



Calculated composition Found in 



(CaO),,FeO . PoO^SiO, Crystals 



CaO 50-54 46-74 



FeO 12-99 not determined 

 SiOo 10-83 11-02 



P0O5 25-63 26-30 



It will be seen that the figures are fairly well in agreement. The 

 material at the author's disposal was not sufficient to enable him to 

 proceed further, therefore he merely wishes to suggest the possibility 

 of some such constitution as that given above. 



One fact has, however, in the author's opinion been fully established, 

 by Stead's work and confirmed by the present analyses that it is not 



