Mr. Watts on the Analysis of Hop- Ash. 57 



the sulphuret of iron, after washing, was oxidized by nitric 

 acid and the oxide of iron precipitated by ammonia. The 

 result was 



Oxide of iron .... 2'7l grs. 

 therefore Phosphoric acid . . . 1*86 ... 



4^ ... 



6. Acetic acid solution (C. II. 2) containing the phosphates 

 of lime and magnesia treated with oxalate of ammonia ; oxa- 

 late of lime washed, dried and ignited, gave 14'23 grs. of car- 

 bonate of lime = 7"97 gi's. of lime. 



7- Liquid tiltei'ed from lime, treated with excess of am- 

 monia, gave 



Pyrophosphate of magnesia 4*37= •< T LL P^*^^P^?^' 

 J t- >■ ° '1^1-60 magnesia. 



S. The quantity of phosphoric acid in combination Avith 

 lime was determined by difference ; thus 



Total quantity of earthy phosphates = 27'26 grs. 



Phosphates of iron and alumina 8 "25 grs. 



Phosphate of magnesia . . . 4*37 ... 



Lime 7'97 ••• 



Making together 20*59 ... 



Therefore phosphoric acid . . 6*67 ... 



This is very nearly the quantity required to form the tri- 

 basic phosphate 5 for the combining number of lime being 

 28, and that of phosphoric acid 71''58, we have 



84:71-38 :: 7-97 : 6-77, 

 which result differs by 0*1 from 6'67. 



The quantity of phosphate of Hme is 7*97 + 6-67 = 14-64. 



9. If we reckon as above (C. II. 4) the quantity of phos- 

 phoric acid in the phosphate of alumina at 2*5 per cent., we 

 have for the total quantity of phosphoric acid in the insoluble 

 part of the ash 6-67 + 2*77 + I'SG-f 2-50= 13'80. Adding to 

 this the quantity contained in the soluble portion (B. I. 5), 

 viz. 0'84, the total amount of phosphoric acid will be 14'64 

 per cent. 



III. Carbonates of Lime and Magnesia. — 1. Liquid filtered 

 from precipitated phosphates (C. II. 1), boiled with oxalate 

 of ammonia, precipitate washed, dried and ignited, gave car- 

 bonate of lime ir04 grs., containing 6*18 grs. of lime and 

 4*86 grs. of carbonic acid. 



2. Filtrate containing magnesia evaporated to dryness ; 

 residue ignited to drive off ammoniacal salts and redissolved 

 in hydrochloric acid. Solution mixed with carbonate of soda 



