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. 



