80 PROCEEDINGS OP THE AMERICAN ACADEMY 



fore only washed upon tlie filter and dried on woollen paper for anal- 

 ysis. In this salt, 



1.1037 gr. ignited with WO.Naj lost 0.1290 gr. = ll.G9f;^ HjO 

 1.976-4 gr. titrated with iodine gave 6.15%, 6.38%, 6.18% AS2O3, 



mean 6.23% 

 1.5652 gr. gave 0.4358 gr. SO^Ba = 18.28% BaO. 



In determining the arsenous oxide the salt was first dissolved in 

 very dilute chlorhydric acid, an excess of sodic bicarbonate being added 

 before titrition. The analyses correspond with the formula 



9 WO3 . AS2O3 . 4 BaO + 21 aq, 



3276 100.00 



The formula may be 



18 WO3 . 2 AsoOg . 8 BaO + 42 aq. 



I have stated above that arsenoso-tungstates pass readily into 

 arsenio-tungstates by oxidation and assumption of two additional 

 atoms of oxygen. It seemed therefore natural to suppose that other 

 simple or complex molecules might also be added to the molecule of 

 arsenous oxide entering into the complex acid. I shall hereafter give 

 the results of a detailed examination of this subject. 



16:8 Sodic Aiseiioso-tungstates. — Arsenous oxide dissolves readily 

 in 10:4 sodic tunestate on boiliu";. When an excess of arsenic is 

 present, the filtrate, after evaporation to the consistency of a syrup, 

 deposits on spontaneous evaporation large colorless prismatic crystals. 

 These dissolve readily in water without decomposition and may be re- 

 crystallized until perfectly pure. After four recrystallizations, 



0.9451 gr. gave with COgNaH and iodine 0.2178 gr. AsgOo = 23.05% 

 0.6128 gr. " " " 0.1416 gr. " =23.10% 



1.1327 gr. gave 0.3237 gr. AsoSg = 23.01% AS2O3 

 0.9225 gr. " 0.5005 gr. WO3 = 54.26% 

 1.0614 gr. « 0.5781 gr. ""=54.46% 

 0.8517 gr. « 0.1238 gr. HjO = 14.54% 



