Ty ee ee ee ee eee es “8 NR, 
Self-sustaining Voltaic Battery. 45 
On the side, at the depth of three inches, is formed a trough 
or tray, an inch wide and half an inch deep, running the length 
of the side. This tray is made with the jars. 
It is indispensable that the jars should be completely water- 
tight, but they are difficult to obtain; and thns far I have had 
none which have given full satisfaction. The best were of 
chemical stone-ware, but only half of them were water-proof, 
A coat of glazing cannot be depended upon for sealing, as in ves- 
sels for culinary and table purposes, as sulphate of zinc penetrates 
even the beautiful stone-ware called “ granite.” 
_ When unable to obtain good rectangular jars, I have used cyl- 
indrical glass jars, and formed the tray with cement on a plate of 
glass or gutta-percha, a little less in width than the inner diame- 
ter of the vessel. The plate can be kept from moving by pro- 
Jecting jogs, which catch on the edge of the vessel. The plate, 
tray, and jogs can easily be moulded in one piece in glass. 
_ The conducting plate of the battery is of the platinized silver 
introduced by Mr. Smee; but the mode of preparing it is differ- 
ent. I first puncture it closely with a square-pointed awl. The 
holes should not be cut with a punch, which removes the metal, 
but formed by pushing the metal up in burs, like those on the 
common tin grater. In this way none of the surface is lost, 
and both sides of the silver are rendered efficient to a single sur- 
face of zine. After the plate has been punctured, it should be 
then be well washed away with hot water, and the plate be pla- 
tinized. I find that: the platinizing is very durable, if the ar- 
rangements for depositing the platinum are made so that the 
bright metallic platinum shall first be deposited, and the amor- 
phous form (black deposits) gradually succeed it. The reguline 
deposit of platinum can readily be obtained by using a mixture of 
chlorid of platinum and chlorid of sodium, (instead of the acid so- 
lution of chlorid of platinum recommended for obtaining the black 
Powder, ) with a train of small batteries and a platinum electrode. 
_ The Conducting plate is attached to a square bar of lead nine 
Inches long, and five-eighths of an inch across the sides. The 
bar rests on the top of the jar, and is kept from moving horizon- 
‘ally by studs near the ends. At the distance of an inch and a 
half from each end of the bar is a pendant an inch long, and of 
pearly the same séction as the bar. ‘The plate is attached to the 
oar by sawing a slit a third of an inch deep in each pendant, in 
the direction of the length of the bar, inserting the silver in the 
~ and thoroughly closing down the lead on the plate. This is 
conveniently done by biting the pendant in the jaws of acom-— 
— ‘Vice. In the side of the bar, near the middle, is 
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