638 



Popular Science Monthly 



is desired, it is best to proceed as follows: 

 Apply a first plate and finish it. Then 

 go over the operation again, dipping in 

 the hot potash solution, rinsing, scouring, 

 dipping again in the cyanide solution 

 and replacing in the plating bath and 

 then finishing and polishing a second time. 

 This will give better results than if a very 

 heavy plate were put on in one operation. 



Articles of different metals or alloy, 

 will not plate at the same time. This 

 will be noticed if there is a soldered joint 

 in the work. Such joints must receive 

 treatment so the solder of the joint will 

 take the plate as well as the rest of the 

 surface. To plate on a soldered joint, 

 make an ounce or two of saturated solution 

 of sulphate of copper and distilled water. 

 Add one-tenth of its volume of sulphuric 

 acid. After the work has received the final 

 scouring and rinsing, and before dipping 

 in the cyanide bath, take a piece of small, 

 clean, iron wire, or a small brush made 

 of iron wire, and dip it in the sulphate 

 solution and draw along the joint. A 

 film of copper will cover the solder instan- 

 taneously and to this the silver will readily 

 adhere. 



If the current is too heavy, the silver 

 film deposited will lie loosely, with a 

 hard dark appearance, and such a plate 

 will not polish. This condition may be 

 remedied by moving the articles farther 

 from the anode and by raising the anode 

 so that less of its surface is in the bath. 

 Too high voltage with too little amperage 

 will also cause a deposit of this kind. 

 Articles being plated should be kept in 

 gentle motion or moved frequently, as 

 the solution has a tendency to settle, re- 

 sulting in uneven plating. 



Too much cyanide in the plating bath 

 will cause the anode plate to assume a 

 white frosted appearance with rough edges. 

 A deposit from such a bath cannot be 

 polished readily. Too little cyanide will 

 cause the anode plate to be covered with a 

 dark deposit having a hard, close-grained 

 appearance, and the plating will be dirty 

 and uneven. When either condition ap- 

 pears, it should be remedied by the addi- 

 tion of a small amount of silver solution, or 

 of the cyanide solution, whichever is 

 necessary. When a bath works properly 

 and the anode remains clean and bright, the 

 only material to be added is a little distilled 

 water occasionally, to counteract evapora- 

 tion. A plating bath will remain fresh for a 

 long time if the evaporation is taken care of, 



and the vessel protected from dust and 

 strong light. 



All operations connected with the actual 

 depositing of the plate and the first 

 finishing should be conducted in dim 

 light. A strong bright light will have a 

 harmful effect on. both the plating solution 

 and the freshly deposited silver. 



A Simple Toy Motor Run with 

 Dry Sand 



THE only materials needed in the con- 

 struction of this sand motor are 2 

 needles, 1 cork stopper, some cardboard and 

 heavy paper, glue and a quantity of fine 

 sand. 



The stopper should be a very large size. 

 On both ends of the cork mark off with a 

 pencil a 6-sided polygon. With a sharp 

 knife cut the cork as shown in Fig. 1. 



Cut six pieces of cardboard for the 

 blades of the sandwheel and glue them to 

 the cork as shown in Fig. 2. Push a needle, 

 eye first, into each end of the cork, as 

 shown. 



fiq.i -— ^— t-,q. 



The sand falling from the cone drops on the 

 edge of the uppermost blade of the wheel 



The framework of the motor shown in 

 Fig. 3 is made from three pieces of card- 

 board glued together. The sand wheel is 

 mounted at the bottom of the frame by 

 pushing the needles through the cardboard. 

 From the top of the frame a paper horn, 

 filled with sand, is suspended by a short 

 piece of thread. The sand sifts down over 

 the blades of the wheel through a hole in the 

 end of the horn. A small cardboard box 

 should be placed under the wheel to catch 

 the sand as it drops from the blades. A 

 small grooved pulley wheel may be attached 

 to one needle end and used with a thread 

 for a belt to turn a light toy machine. The 

 wheel can be fastened with a bit of wax. 

 The sharp ends of the needles should be 

 broken off. — E. P. Thornton. 



