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LESSORS IN KI7ECTRIOITY. 



. A couple of pads, composed of 

 three or four layers of silk, about eight 

 or ten inches square ; 



/. A board about 18 inches square, 

 and a piece of india-rubber ; 



<7. Some very narrow silk ribbon, n, 

 and a wire loop, w, like that shown in 

 fur. 1, in which sticks of sealing-wax, 

 tubes of gutta-percha, rods of glass, or n 

 Walking-stick, may be suspended. I 

 cl)ooso a narrow ribbon because it is con- 

 venient to have a suspending cord that 

 will neither twist nor untwist of itself. 



(I usually employ a loop with the two 

 ends, which arc here shown free, soldered 

 together. The loop would thus be un- 

 broken. But you may not be skilled in 

 the art of soldering, and I therefore 

 choose the free loop, which is very easily 

 constructed. For the purpose of suspen- 

 sion an arrangement resembling a towel- 

 horse, with a single horizontal rail, will 

 be found convenient). 



FIG. 2. 



h. A straw, 1 i', fig, 2, delicately sup- 

 ported on the point of a sewing needle N. 

 This is inserted in a stick of sealing-wax 

 A, attached below to a little circular plate 

 of tin, the whole forming a stand. In 

 fig. 3 the straw is shown on a larger 

 scale, and separate from its needle. The 

 shore bit of straw in the middle, which 

 serves as a cap, is stuck on by sealing- 

 wax. 



t. Tke name "amalgam" is given to 

 a mixture of mercury with other metals. 

 Experience has shown that the efficacy of 

 a silk rubber is vastly increased when it 

 is smeared over with an amalgam formed 

 of 1 part by weight of tin, 2 of zinc, and 

 6 f mercury. A littlo lard is to be first 



smeared on the s-ilk, and the amalgam is 

 to be applied to the lard. The amalgam. 

 if hard, must be pounded or biuised.with 

 a pestle or a hammer until it is soft. 

 You can purchase sixpenny- worth of it at 

 a philosophical instrument maker's. It 

 is to be added to your materials. 



fc. I should like to make these pages 

 suitable for boys without much pocket- 

 money, and, therefore, aim at economy 

 hi my list of materials. But provide by 

 all means, if you can, a fox's brush, such 



as those usually employed in dusting 

 furniture. 



5. Electric Attractions. 



Place your sealing-wax, gutta-percha 

 tubing, and flannel and silk rubbers be- 

 fore a fire, to insure their dryncss. Be 

 specially careful to make your glass 

 tubes and silk rubbers not only warm, 

 but hot. Pass the diied flannel briskly 

 once or twice over a stick of sealing-wax 

 or over a gutta-percha tube. A very 

 small amount of friction will excite the 

 power of attracting the suspended straf 

 as shown in fig. 2. Repeat the experi- 

 ment several times and cause the straw to 

 follow the attracting body round and 

 round. Do the same with a glass tube 

 rubbed with silk. 



I lay particular stress on the heating of 

 the glass tube, because glass has the 



