144 Journal of the Asiatic Society of Bengal. {| April, 1906, 
solution is the only method by which a polyvalent silver compound 
can be obtained in any quantity. Other methods have been 
«lescribed for the preparation of silver dioxide. Wohler states 
that he obtained silver dioxide as a black crust on a silver anode 
during the electrolysis of dilute sulphuric acid (Lvebiys Ann. Chem., 
Leipzig, 146, p. 263), but the method gives an exceedingly poor 
yield, and it is difficult to obtain sufficient even for analysis. 
Schiel has described the preparation of silver diogide by the 
action of ozone on normal silver oxide, Ag,O (Liebigs Aun. Uhem., 
Leipzig, 182, p. 322); and Berthelot has given reasons for the 
supposition that an oxide, Ag,O,, is formed on the addition of 
the electrolysis of silver nitrate solution (Vischer, Joc. cit. ; Gmelin 
and Mahla, loc. cit. ; Wallquist in Journ. Prakt. Chem, 31, p. 179; 
Grotthus, in Gilbert Ann. 61,1819, p. 60; Béttger Zeitschrift fir 
Chemie 1870, 82 and Berichte 1873, 1396). The whole question 
of the valency exhibited by silver in its per-compounds ap 
therefore, subject to doubt. It appeared probable that the 
dioxide of silver, Ag,O,, had never been obtained, and a whole 
eri ormulae, wiz., Ag,O;,, Ag,O,, Ag,O., AgO, Agi: 
Ag 0); and Ag,,O), had equal olay rouenchdethe valency ot 
silver in its per-compounds, 
Black powders are obtained at the anode during the electro- 
For the product of the electrolysis of aqueous silver sulphate 
solution Mulder (Rec. ‘'rav. Chim, Leiden, 18, p- 91; 19. p- 115) 
From these considerations I was led to examine in the first 
place the composition of the product obtained during the electro- 
product. This will not stand washing with warm water or con 
pare Bran g with warm water © 
with filter-paper or drying in the steam-oven, but if it be washed 
