A. A. Ramsay 287 



41-54 grams P205- Quadruplicate gravimetric determinations gave 

 41-664 grams P2O5 present in the 500 c.c. solution. 



Preparation of tricalcic phosphate from 3 equivalents CaO to 

 1 equivalent P2O5 preparation No. 9. 



225 c.c. of the above phosphoric acid solution containing 18-745 grams 

 P2O5 were taken. 22-1796 grams pure freshly ignited lime prepared by 

 igniting pure calcium carbonate was weighed out. About 100 c.c. of 

 water was added to the lime, then the phosphoric acid added, stirred 

 well, and allowed to stand with frequent stirring for one hour. 



The precipitate was filtered off and dried at 100° C. 



Product obtained by mixing 2 equivalents of CaO with 1 equivalent 

 PgOg preparation No. 10. 



11-2644 grams pure lime prepared as above described was weighed 

 out. To this was added about 100 c.c. water, and 171-5 c.c. phosphoric 

 acid solution containing 14-2816 grams P2O5. The mixture was well 

 stirred at frequent intervals during an hour. At the end of that time 

 the precipitate was filtered off, washed well with water, and dried at 

 100° C. The weight of the product obtained was 20-74 grams. 



Upon analysis preparation No. 9 was found to contain : 



Lime (CaO) ' 50-12 



Phosphoric acid (P.JO5) 42-36 



Water „"'52 



100-00 

 By calculation the above lime and phosphoric acid corresponds to 

 3CaO : P2O5 or pure tricalcium phosphate. The water of crystallisation 

 present indicates that the formula of the tricalcic phosphate is 

 Ca3P208l-384H20 or SCagPaOgllHaO. 



This preparation when dried at 125° C. has apparently the com- 

 position of Ca3P208l-3H20 or 10Ca3P2O8l3H2O. 



The analysis of preparation No. 10 (from 2 equivalents CaO to 

 1 equivalent P2O5) showed this product to consist of: 



Lime (CaO) 44-58 



Phosphoric aoid (P/).,) 44-30 



Water ... ".. 1H12 



100 00 * 

 By calculation the above numbers are found to indicate a mixture 

 of di- and tricalcic phosphate. Thus : 



CaO HoO P2O5 Water 



Dicalcic phosphate ... 15-G63 2-517 19-858 — = 38-038 



Tricalcic phosphate ... 28-917 — 24-442 — = 53-359 



Water of crystallisation ... — — — 8-603 = 8-603 



44-580 2-517 44-300 8-603 =100-000 



