

The Phosphates of America. 147 



EXAMPLE. 



Weight of the carefully dried "Schrotter" charged with] 



Two grammes Phosphate in A I 



Diluted HC1 in B }> 33.672 



Concentrated H 2 SO 4 in C j 



Weight of the carefully dried apparatus at the end of two i 

 hours, after the prescribed manipulation f 



Loss in weight by 2 grammes phosphate 0.087 



Equal 0.0435 in 1 gramme, or 4.35 per cent. 



Insoluble Siliceous Matters. 



Five grammes of the original sample in its normal state are accu- 

 rately weighed out and placed in a porcelain dish with about 30 c.c. 

 of aqua regia. The dish is placed upon a sand or air bath, cov- 

 ered with an inverted funnel, gradually heated, and evaporated to 

 dryness ; care being taken to avoid any spurting and consequent 

 loss. As soon as it is dry, the residue is moistened with pure con- 

 centrated hydrochloric acid, and again evaporated to complete dry- 

 ness, after which the heat of the bath is increased to 125 C. and so 

 maintained for about ten minutes. When it has become cool the 

 silica will all be insoluble, and the residue is treated with 50 c.c. 

 of concentrated hydrochloric acid and allowed to remain in this 

 contact for fifteen minutes. The acid is then diluted, filtered 

 through an ashless filter, and the porcelain dish and the filter care- 

 fully washed with hot water until the filtrate measures 250 c.c. 

 The residue on the filter, which should be quite white, is now dried 

 in the oven, calcined and weighed. The weight -f- 5 = insoluble 

 siliceous matter in 1 gramme of the material. 



Sulphuric Anhydride (SO 3 ). 



Twenty -five c.c. of the filtrate from the siliceous matter, repre- 

 senting 0.50 gramme of the phosphate, are placed in a beaker, 

 boiled, and treated while boiling with 5 c.c. of a saturated solution 

 of barium chloride. The hot liquid is brought upon a small ash- 

 less filter ; the beaker and the filter are well washed with boiling 

 water until the last washings show no trace of chlorides ; and the 

 filter is then dried, calcined and weighed. The weight X .3429 

 X 2 = sulphuric anhydride (SO 3 ) in 1 gramme of the material. 



N.B. The words "ashless filter" are used on this, and on all 

 subsequent occasions, only in a comparative sense, and are meant 

 to indicate the round cut filters, washed in hydrochloric and 



