6Q 



PROCEEDINGS OF THE AMERICAN ACADEMY 



Mg 2 P 2 7 . P 2 6 found. P 2 5 required. 



Error. 



Per cent, 

 error. 



XIV. 



XV. 



(96) 0.0430 gr. 0.0275 gr. 0.0269 gr. + 0.0006 gr. +2.23 



(97) 0.0431 gr. 0.0276 gr. 0.0269 gr. +0.0007 gr. +2.60 



(98) 0.0436 gr. 0.0279 gr. 0.0269 gr. + 0.0010 gr. -j-3.72 



(99) 0.0440 gr. 0.0281 gr. 0.0269 gr. -j-0.0012 gr. -j-4.46 



(100) 0.0441 gr. 0.0282 gr. 0.0269 gr. -fO.0013 gr. +4.83 



(101) 0.0447 gr. 0.0286 gr. 0.0269 gr. + 0.0017 gr. +6.32 



In experiments (102) to (115) inclusive, 5 cm. 3 of strong hydro- 

 chloric acid were added to each portion of phosphate and tungstate, 

 and to portions (112), (113), (114), and (115) 0.5 gr. of citric acid; 

 to every portion, excepting (108) and (109), ammonia in distinct 

 excess; to (108) and (109) ammonia until the precipitate which 

 formed at first was redissolved hut not until the solution smelled of 

 ammonia ; to all, individually, 20 cm. 8 of magnesic chloride mixture 

 from which the ammonia had been expelled, and, after the settling of 

 the precipitate, ammonia in strong excess. 



XV. 



XVI. 



XV. 



IX.-! 



I (112) 



(113) 

 (114) 

 I (H5) 



Mg 2 P 2 7 . 



0.0436 gr. 

 0.0441 gr. 



0.0446 gr. 

 0.0454 gr. 

 0.0459 gr. 

 0.0465 gr. 



0.0498 gr. 

 0.0543 gr. 



0.3251 gr. 

 0.3262 gr. 

 0.3381 gr. 

 0.3398 gr. 

 0.3423 gr. 

 0.3429 ffr. 



P 3 5 found. 



0.0279 gr. 

 0.0282 gr, 



0.0285 gr. 

 0.0290 gr. 

 0.0294 gr. 

 0.0297 gr. 



0.031 8 gr. 

 0.0347 gr. 



0.2079 gr. 

 0.2086 gr. 

 0.2178 gr. 

 0.2187 gr. 

 0.2190 gr. 

 0.2193 gr. 



P a 5 required. 



0.0269 gr. 

 0.0269 gr. 



0.0269 gr. 

 0.0269 gr. 

 0.0269 gr. 

 0.0269 gr. 



0.0269 gr. 

 0.0269 gr. 



0.2017 gr. 

 0.2017 gr. 

 0.2017 gr. 

 0.2017 gr. 

 0.2017 gr. 

 0.2017 gr. 



Error. 

 +0.0010 gr. 

 +0.0013 gr. 



+0.0016 gr. 

 +0.0021 gr. 

 +0.0025 gr. 

 +0.0025 gr, 



+0.0049 gr. 

 +0.0078 gr. 



+0.0062 gr, 

 +0.0069 gr. 

 +0.0161 gr. 

 +0.0170 gr, 

 +0.0173 gr, 

 +0.0176 gr. 



Per cent, 

 error. 



+3.72 

 +4.83 



+5.95 

 +7.80 



+9.29 

 +9.29 



+ 18.21 

 +28.99 



+3.04 

 +3.39 

 +7.91 



+8.35 

 +8.49 

 +8.64 



Phosphomolybdates. 



In each of the following experiments upon the determination of 

 phosphoric oxide in phosphomolybdates, 0.5 gr. of molybdic oxide 

 (M0 3 ) were dissolved in ammonia and added to 40 cm. 8 of a phos- 

 phate solution, 5 cm. 8 of strong hydrochloric acid added and ammonia 



