OF ARTS AND SCIENCES. 5 



it by passing a current of carbonic dioxide for some days through a 

 solution of the normal tungstate. Forcher gives the formula 



5W0 3 . 2Na 2 0+ 12H 2 0, 



and suggests, though without adducing any evidence in support of his 

 view, that it may be a double salt, with the formula 



3 W0 8 . Na 2 + 2 W0 3 . Na 2 0. 



Marignac, who appears to have been unacquainted with Forcher's paper, 

 soon afterward described the same salt as an accidental product, attrib- 

 uting to it the formula 



5W0 8 .2Na 2 0+ 11H 2 0. 



Finally, Lefort * obtained it by the action of acetic acid upon a solu- 

 tion of the normal tungstate, and, without citing the results of Forcher, 

 also proposed the formula 



5W0 8 . 2Na 2 + 11H 2 0. 



I have obtained the salt by the following process, which appears to be 

 the most convenient. Normal sodic tungstate, 



W0 3 .Na 2 + 2aq, 



is to be dissolved in water, and acetic acid added, in small portions at 

 a time, to the boiling solution, until the reaction becomes strongly 

 acid. Alcohol then precipitates the 10:4 tungstate as a heavy oil, 

 which soon becomes a solid mass. The solution on standing some 

 days deposits colorless crystals, which are usually much twinned, and, 

 according to Marignac, belong to the monocliuic system. They efflo- 

 resce readily in dry air and are soluble, according to Forcher's deter- 

 mination, in 12.6 parts of water at 22° C. When heated they fuse to 

 a yellow liquid, which on cooling gives a white crystalline mass nearly 

 insoluble in cold water but dissolved by long boiling. I assign to the 

 crystallized hydrate the formula 



1 WO a . 4 Na 2 + 23 H 2 0, or 1 W0 3 . 4 Na 2 . 2 H 2 -f 2 1 aq, 



with which all the analyses agree very closely. Of the salt, 



»2 gr. lost 0.1963 gr. by ignition = 13.88% 



gr. gave 0.3194 gr. W0 3 = 77.99% 



■jj ( 1.1182 gr. lost on ignition 0.1558 gr. water = 13.94% 

 ' (0.8950 gr. gave 0.6968 gr. W0 8 = 77.85% 



* Loc. cit. 



(1.4152 



(0.4095 



