OP ARTS AND SCIENCES. 69 



The formula given must be doubled to give a structural scheme in 

 which all the terms will be symmetrically arranged. 



It appears at least probable that classes of antimonio-vanadates and 

 antimonio-vanadico-vanadates also exist, but the few experiments which 

 I have been able to make with the small quantity of material at my 

 disposal are not conclusive as to either point, and I hope to be able to 

 return to the subject. 



VANADICO- VANADATES. 



Salts belonging to this series are formed when solutions of vana- 

 dates are mixed with those of vanadic dioxide, and when vanadates 

 undergo partial reduction by the action of any reducing agent. These 

 compounds are often crystalline and well defined. They have, usually 

 at least, a green color. 



2 : 4 Ammonic Vanadico -vanadate. — When a solution of vanadic 

 dioxide in chlorhydric acid is added to one of ammonic metavanadate, 

 u fine green crystalline salt separates, but slightly soluble in either cold 

 or hot water. Tlie salt analyzed was not recrystallized, but merely 

 washed with cold water and dried upon woollen paper. Of this salt, 



( 1.0470 gr. gave 0.0159 gr. VO2 by KMnO, = 15.21 ^ VO. 

 ( 1.0470 gr. " 0.0701 gr. V^O^ " = 66.98% Y^O^ 



0.1470 gr. " 0.0066 gr. (NHJ2O = 4.50% 



The analyses lead to the formula 



1093 100.00 



The following may serve as starting-points for further investigation. 

 When solutions of sodic divanadate and manganous sulphate are mixed 

 and allowed to stand in an open vessel, very dark green well-defined 

 crystals are gradually deposited. There is here, doubtless, reduction 

 from the presence of dust. When a solution of vanadic dioxide in 

 chlorhydric acid is mixed with solutions of the sulphates of zinc, copper, 



