Popular Science Monthly 



Rejuvenating Electric Lamps 



DON'T throw away your burnt-out 

 electric lamps. They can be re- 

 newed by this simple method: 



File off the tip carefully so that the 

 globe does not crack. With a pair of 

 tweezers, twist the broken filament 

 together. Obtain from the druggist a 

 piece of yellow phosphorus for five or 

 ten cents. Insert a piece of it, about 

 half the size of a pea, in the bulb. 

 Cautiously heat the top of the globe by 

 means of a Bunsen burner, and melt a 

 piece of chemical glass over the hole, 

 closing it completely. 



The phosphorus unites with the o.xy- 

 gen in the bulb to form phosphorus 

 trioxide, a cloudy substance, which will 

 settle in a few days. The globe is now 

 filled with nitrogen. 



The greatest caution must be exercised 

 in the use of the phosphorus. It must 

 be handled under water entirely, and 

 with tweezers. Do not touch it. 



An Exciter for Electroscopes 



THE electrosta- 

 tic exciter 

 described in the 

 October number of 

 the Popular 

 Science Monthly 

 is rather too power- 

 ful for use in charg- 

 ing electroscopes. 

 The following is a 

 handy arrangement 

 involving no risk of damaging the gold 

 leaves. 



Find a small glass jar without a neck, 

 and coat with shellac inside and out. 

 Attach a piece of fur inside the jar, the 

 skin side next the glass using the same 

 solution of shellac in alcohol, as an 

 adhesi\-e. Select a small brass tube 

 closed at one end, that will just slip in- 

 side the fur, and after fitting in a .sound 

 cork, insert a glass rod for a handle. 

 Cover the cork with sealing wax. 



Keep the metal tube inside the fur- 

 lined jar when not in use. By merely 

 withdrawing the former it will acquire 

 a negative charge by rubbing against 

 the fur. From the metal tube an electro- 

 scope can be charged negatively by 

 contact, or positively by induction. 



Exciting device 



Cariart of Dry Baffery 

 Dip fhis end of Carbon in fbraffine 



Zjnc of Dry 8a fiery 



TacM- 

 3e/ution of 5a/-Anunoniac ■ 



IVixx^n sfnps 

 fycfiec/ fo Znc 



Carbon 



Jar-- 



WL 



A few minutes' work makes a wet battery 

 from a dry one 



A Wet Battery From a Dry One 



THE zinc and carbon of an exhausted 

 dry battery may be used to make a 

 wet battery, as shown in the illustration. 

 The carbon should be o\en-baked to 

 dry out all impurities. The bottom of 

 the zinc can is removed and a number of 

 wooden strips wedged in, as shown; 

 the carbon should then be tacked in 

 place. The upper end of the carbon is 

 dipped in parafifine, to prevent creeping 

 of the salt. After placing a solution of 

 sal-ammoniac in the can, the zinc and 

 carbon are inserted. — Filvnk Harazlm. 



Interference of Lighting Circuit by 

 Static Electricity 



THE writer had an electric light that 

 would not last more than an hour 

 without burning out; but during the 

 time that it was in use it gave a very 

 bright light. About nine inches from 

 the lamp cord a belt rubbed at a cross, 

 producing static electricity by means of 

 the friction at the cross. This condition 

 was corrected as shown in the drawing: 

 L is the light. B is the belt, crossing at 

 C ; / is a piece of iron connected by a 

 copper wire to a water pipe. G. C. is a 

 ground clamp. 



One more static difficulty overcome 



