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Page:Popular Science Monthly Volume 90.djvu/299

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Popular Science Monthly

��283

��Utilizing Tin Cans to Make Containers for Dry Batteries

THERE seems to be very little use for the emptied tin can — the kind in which soups and vegetables are sold. How- ever, one inventor has proven their worth by using them as containers for dry batter- ies. The illustration shows three of these tins taking the place of zinc cylinders as the containing vessels and positive element of the cell. They were prepared in the following manner: The inner contents of four old exhausted dry cells, consisting of powdered carbon, peroxide of manganese and graphite, or black lead (plumbago) were taken and reduced to a powder by crushing with a mallet.

Four disks of white blotting paper were cut to fit the interior of the bottom and the same number of pieces were cut to lay in around the interior of the can, care being taken to have about ^4 in. project above the top so as to form a fold over the edge of the can. The blotting board was so folded at the bottom that it made a turned- in portion, and two more disks of blotting paper were then pressed into the interior to make a complete cell or well of paper all around the inside and bottom of the can. The dried material was then wet with a saturated solution of equal parts of chloride of zinc and sal ammoniac so as to convert the mixture into the same dry state. Each carbon-rod that had been removed from the old cells was heated at the bottom-end and for half its length in the flame of a gas-stove, and then allowed to cool. The cans were then filled nearly to the top with the chemical mixture which completely soaked the blotting-board lining. The second and third cans were treated similarly by pouring the contents of the first into the second and then into the third. The cans were then turned upside down foi a short time until the lining became well soaked with the saline solution. Then they were ready for the filling. A couple of table'spoonfuis of the dampened carbon mixture was then placed in each can and a carbon-rod that had been dipped in the saline solution was pressed into the mixture. More of the carbon mixture was placed in around the rod and rammed down tight with a stout piece of wood driven with a wood" mallet. The filling and ramming was continued until the can was filled to within 3^ in. of the top. The wet blotting-paper lining was then carefully turned over the top of the carbon mixture and pressed

��down with the flat end of a clean stick, care being taken to keep the carbon mixture from flowing over and connecting the carbon-rod with the metallic part of the can, thus forming a short circuit and quickly exhausting the electrical energy generated. The cell was completed by covering the turned-over edge of the paper lining with a little dry sand or a mixture of dry sand and plaster of Paris. It was then filled to the brim with melted pitch. Common resin may be used for this pur- pose, but it is more expensive.

Each cell should test about 6 amperes.

���Ordinary tin cans used for containers for the positive element of a dry cell battery

The three cans coupled in series gave about 2)4: volts, which rang a bell with consider- able vigor. After several weeks of use these tin-can cells showed no decline in power. Connections are made just as to the ordi- nary dry cell. — Alfred J. Jarman.

��An Oil-Gage for the Automobile Gas-Tank, Made from a Broomstick

TAKE a broom handle and saw off a 2-ft. length and saw a slot in one end to fit over the pet cock oil-gage. With this gage you can measure the gas and reach under the fender and see if the cylinder oil is right without getting the hat or coat soiled.

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