1815.] Description of an Elementary Galvanic Battery. 209 
of a quadruple compound (the properties of which are given in ex~ 
periment 10) consisting of oxide of tungsten, potash, ammonia, 
and muriatic acid ; and only a very small quantity of tungstate of 
ammonia can be obtained. ‘Thisshows us the necessity of employing 
pure oxide of tungsten in the formation of tungstate of ammonia. 
8. Besides the yellow and dark blue oxides of tungsten, there 
seems to exist another of a dark brownish red or reddish brown 
eolour. It may be obtained by the application of heat to the tung- 
state of ammonia, in consequence of the deoxidizing property of 
the ammonia. In respect to the degree of oxidation, it seems to 
lie between the yellow and the blue oxides. 
4. The complete reduction of oxide of tungsten by the method 
above described is a much easier process than the fusion of the re- 
duced metal. This holds likewise with molybdenum, manganese, 
and other difficultly fused metals. 
5. It is exceedingly probable that the failure which different 
chemists have experienced in their attempts to reduce the oxide of 
tungsten, was owing to a mixture of the triple compound with the 
oxide employed by them. 
6. The statement of the Elhuyarts and of Allen and Aikin re- 
specting the specific gravity of this metal is confirmed. We may 
consider 17*4, the mean of preceding statements, as near the truth. 
The other statements respecting the colour, lustre, hardness, and 
brittleness, of our metal, are likewise confirmed. 
7. The presence of a portion of Scheele’s tungstic acid in the 
oxide of tungsten prevents its complete reduction, and causes it to 
run into a slag. 
ee 
Articie VII. 
Description of an Elementary Galvanic Battery. By W. Hyde 
Wollaston, M.D. Sec. B.S. 
(To Dr. Thomson.) 
DEAR SIR, 
AGR&EAMLY to your request, I now send you a description of a 
small battery which I showed you some time since, and shall feel 
obliged by the insertion of it in your Annals, 
Since the ignition of metallic wires is highly instructive with 
Tespeet to the vast quantity of electricity evolved during the solution 
of metals, 1 made, about three years since, a series of experiments 
for the purpose of ascertaining the most compendious form of appas 
ratus by which visible ignition might be shown. 
The result of these trials was, that a single plate of zinc one inch 
square, when rightly mounted, is more than sufficient to ignite a 
Vo. VI. N° I, O 
