120 PROCEEDINGS OF THE AMERICAN ACADEMY 



ration of antimony from tungsten and from molybdenum, a sufficient 

 quantity of an alkaline carbonate is added to convert all the higher 

 oxides present into neutral salts. Under these circumstances, no in- 

 soluble compound of molybdenum is formed, and the tin separates in 

 brio-lit metallic globules. Phosphoric acid may be determined in these 

 salts after separating the whole of the tin and the greater part of the 

 molybdenum by means of sulphydric acid. Molybdic oxide is esti- 

 mated most advantageously by difference. 



16:4:3:3 Ammonic Stanno-pJiospho-mohjhdate. — When a solution 

 of stanno-chloride of ammonium, SnCl,;(NH4)2, is poured into a hot 

 solution of acid ammonic phospho-molybdate, 



10 M0O3 . 2 P2O, . 5 (NH,).0 + 7 aq, 



a fine bright yellow crystalline precipitate is formed, which quickly 

 settles and leaves a colorless solution. The salt is almost insoluble, 

 even in boiling water, and may perhaps find an application in the sep- 

 aration and quantitative estimation of tin. On boiling with mercu- 

 rous nitrate it gives a buff-yellow crystalline mercurous salt. Under 

 the same circumstances cupric sulphate yields yellowish-green crystals, 

 and argentic nitrate a very pale yellow, not distinctly crystalline salt. 

 An excess of ammonia readily decomposes the salt with separation of a 

 white gelatinous mass. Of this salt, 



0.8648 gr. gave 0.1023 gr. metallic tin = 15.19 % SnOg 

 2.3780 gr. " 0.3865 gr. P.O.Mg., = 10.40 % Vf>^ 

 1.2021 gr. " 0.2016 gr. " =10.73% " 



1.0130 gr. " 0.3839 gr. (NH4)20 = 3.79 % 

 1.7170 gr. lost on ignition 0.2793 gr. = 16.27 % 



The analyses give the formula 



16 M0O3 . 4 SnOa . 3 P2O5 . 3 (NH4)20 + 28 aq, 



3990 100.00 



