OF ARTS AND SCIENCES. 61 



III. 



In experiments (21) to (26) inclusive 40 cm. 8 of magnesic sul- 

 phate mixture from which the ammonia had been removed by boiling 

 were in each case added to 40 cm. 8 of the phosphate solution ; in 

 (21), (22), (23), and (24) directly, in (25) and (26) after acidifying 

 with 5 cm. 8 of strong hydrochloric acid and then making faintly "but 

 distinctly ammoniacal. In every case dilute ammonia was added 

 gradually at first, and 5 cm. 8 of strong ammonia after, the settling of 

 the precipitate. Portions (21) and (22) were precipitated hot. 



Mg 2 P,0 7 - P 2 6 found. P 2 O s required. Error. ^error.*" 



f (21) 0.3112 gr. 0.1991 gr. 0.1875 gr. +0.0116 gr. +6.18 



I (22) 0.3114 gr. 0.1992 gr. 0.1875 gr. +0.01 17 gr . +6.24 



' (23) 0.3028 gr. 0.1936 gr. 0.1875 gr. + - 0061 g r - +3.25 



(24) 0.3048 gr. 0.1949 gr. 0.1875 gr. +0- °74 gr. +3.94 



(25) 0.3469 gr. 0.2219 gr. 0.2142 gr. +0.0077 gr. +3.59 

 ' (26) 0.3514 gr. 0.2248 gr. 0.2142 gr. +0.0106 gr. + 4 - 94 



For experiments (27) to (39) inclusive portions of 40 cm. 3 each of 

 the phosphate solutions were taken. To portions (27) and (28) were 

 added 12 cm. 3 of magnesic chloride mixture; to (29) and (30) 5 cm. 3 

 of strong hydrochloric acid, strong ammonia to neutralization and 

 10 cm. 3 beside, and then 12 cm. 8 of magnesic chloride mixture ; to 

 portions (31) to (39) inclusive 5 cm. 3 of strong hydrochloric acid, 

 20 cm 8 of strong ammonia and 10 cm. 8 of magnesic chloride mixture, 

 5 cm. 3 more of the same being added, except in experiment (31), 

 after the settling of the precipitate. 



VI J 



MgoP 2 7 - PAtound- P 2 5 required. Error. ^rnfr" 4 ' 



' (27) 0.3430 gr. 0.2194 gr. 0.2195 gr. —0.0001 gr. —0.04 



(28) 0.3438 gr. 0.2199 gr. 0.2195 gr. +0.0004 gr. +0.18 



(29) 0.3425 gr. 0.2191 gr. 0.2195 gr. —0.0004 gr. —0.18 



(30) 0.3435 gr. 0.2197 gr. 0.2195 gr. +0.0002 gr. +0.09 



