74 CENTRAL SCIENTIFIC CO., CHICAGO, U. 8. A. 



BATTERY DIRECTIONS 



Amalgamating. A good method for amalgamating a zinc element is to dip it into acid, then pour a 

 few drops of mercury on the surface and rub in with a piece of cloth attached to a stick. This is per- 

 haps the best and quickest method although the most expensive. 



Amalgamating Fluid. 2 ounces mercury, 1 ounce aqua regia, 10 ounces water. Dip zinc into solution 

 and then wash with water. No need of brush or rag. Zinc element should be thoroughly cleaned before 

 amalgamating by means of a metal scratch brush or coarse emery cloth. 



Bunsen Battery. Outer cell contains amalgamated zinc plate dipping into dilute sulphuric acid (by 

 weight 10 parts water to 1 part acid). In inner porous cup, a piece of carbon dips into nitric acid of 

 full strength. Obnoxious nitrogen oxide fumes may be suppressed in a large measure by the addition 

 of a small quantity of potassium dichromate. If desired the nitric acid may be replaced by a chromic 

 acid solution. (Sec Sulpho-Chromic Salt below.) 



Burn-Boston Battery. To make active, ready for use, add plain water. 



Carbon Cylinder Battery. Place 6 ounces ammonium chloride in jar and fill with water to two- 

 thirds its capacity. Stir well until the salt is entirely dissolved. Place elements with zinc inside carbon 

 cylinder as illustrated. 



Columbia Dry Battery. Should be entirely discarded after its amperage has dropped to a point un- 

 fitting it for use, as it cannot be recharged. 



Daniell Battery. The zinc element is placed in a porous cup containing sulphuric acid (1 part acid 

 to 20 parts water, by weight). The copper element encircles a porous cup and dips into saturated copper 

 sulphate solution, kept continually saturated by the addition of an excess of copper sulphate crystals on 

 bottom of jar. Solution is more effective by addition of few cubic centimeters of sulphuric acid. 



(In our No. 958 a pocket is provided for holding excess crystals of copper sulphate.) 



Edison Primary Battery. The exhaustion of the. cell is indicated by holes appearing in the lower 

 part of the zinc plates. When this point is reached, a complete renewal (see No. 967) should be obtained 

 as the parts are so proportioned that all become exhausted at the same time. Directions are furnished 

 with each renewal. 



Fuller Battery. Fill glass jar half full of chromic acid solution made from Sulpho-Chromic Salt 

 (see below), place 1 teaspoonful mercury and 2 tablespoons full of common salt in the porous cup and 

 fill with water to l 1 /^ inches of top. The carbon element containing the porous cup is then placed in the 

 glass jar, the zinc is placed in the glass jar and the cover over it. The solution should fill the glass jar to 

 within an inch of the top. 



Gravity Battery. This type of battery is merely a form of Daniell cell, where the two solutions are 

 kept separate by their difference in specific gravity. Place 2 pounds copper sulphate crystals in bottom 

 of jar with copper element. Add clear water to fill the jar when elements are in position. Suspend zinc 

 over edge of jar and connect the two plates through a resistance of 10 ohms or more. When the solutions 

 have separated, that around the zinc plate being colorless, while that around the copper is blue, the cell 

 is ready for action. If during this time the zinc plate has become covered with precipitated copper, it 

 should be taken out and brushed off until the surface is bright. The separation of the two solutions 

 may be hastened by adding some crystals of zinc sulphate or a small amount of dilute sulphuric acid. 



Grenet Battery. In this cell, the zinc plate between two carbon plates dips into a chromic acid solu- 

 tion. (See below.) When this coll is exhausted, the rich reddish color of chromic acid will be replaced 

 by a muddy dark green color. 



Chromic Acid Solution. There are many different formulae, but the most convenient method of 

 making a generally useful acid is by simply dissolving prepared chromic acid salt in water. (See Sulnho- 

 Chromic Salt, below.) 



A useful formula is, 30 parts sodium dichromate, 100 parts water arid 23 parts sulphuric acid (sp. 

 gr. 1.845) ; all by weight. 



LeClanche Battery. Directions furnished under carbon cylinder cell apply to this type of cell, ex- 

 cept that zinc rod is placed outside of porous cup. 



Plunge Battery. Elements and directions under Greuet type apply to this type of battery. 



Samson Battery. Directions furnished under carbon cylinder cell apply to this type of cell. 



Storage Batteries. These cells make the most convenient source of electrical supply, providing the 

 laboratory is equipped for charging. Full directions for use and for charging accompany each cell. 



BATTERY FLUID 



CENCO SULPHO-CHKOMIC SALT. (Formula patented.) For making Battery Fluid for Plunge 

 Batteries and Grenet Cells and to replace the Nitric Acid in Grove and Bunsen Cells it will be found 

 that Cenco Sulpho-Chromic Salt is without an equal. Its use does away with all handling of acids in 

 liquid form. One jar (2 Ibs.) is sufficient for three quarts of battery fluid Per jar $0.80 



