12 PROCEEDINGS OF THE AMERICAN ACADEMY 



The formula 12 W0 3 . 5 K 2 -f- 10 aq requires 81.02% WO, 

 and 5.25% II 2 0. 



Amnionic Tangstates. — When a solution of amnionic chloride is 

 added to one of the 10:4 sodic tungstate, beautiful white talcose scales 

 are thrown down, which are but slightly soluble in cold water. After 

 washing, they may be dissolved in boiling water without evolution of 

 ammonia and recrystallized. The analyses of this salt agree fairly 

 well with the formula 



10 W0 3 . 4 Na.0 -f 4 {10 W0 8 . 4 (NH 4 ) 2 0} + 50 aq, 



as the following analyses show : — 



j (0.5658 gr. gave 0.4851 gr. W0 3 =85.74% 



1 0.5602 gr. loston ignition 0.0690gr. water and ammonia = 12.31 % 



13580 100.00 99.95 



Analyses (I.) and (II.) are of different preparations of the same 

 salt. When commercial ammonic tungstate (containing a little sodic 

 oxide) is dissolved in ammonia, and acetic acid is added to the filtered 

 liquid, a white slightly soluble salt is obtained which after recrystal- 

 lization has the formula 



12W0 3 . 5(NH 4 ) 2 + 6aq. 

 In this salt : 



0.9293 gr. lost on ignition 0.1087 gr. = J X1 - 69 % N "* and H 2 ° 

 g fo & (88.31% W0 3 



0.5366gr. » " 0.0626 gr. = fH.66% NH 8 andH,0 



6 s (88.34% W0 3 



0.6602 gr. gave 0.2039 gr. platinum = 8.15% (NH 4 ) 2 



1.1241 gr. " 0.3370 gr. « = 7.92% " 



Calc'd. Mean. Found. 



12 WO, 2784 88.32 88.32 88.34 88.31 



5(NH 4 ) 2 260 8.24 8.03 8.15 7.92 



6H 2 108 3.44 3.64 3.51 3.77 



3152 100.00 99.99 



