120 ELECTRO-PLATING. 



nevertheless all these metals and alloys may be, and are, plated, but 

 cannot give the satisfaction which brass, copper, or German silver 

 afford, 



Electricity given off from Sandy Deposits. We may mention that 



when depositing silver upon a large surface, and the solution or 

 battery being in the condition to give the sandy deposit, or rather 

 when the deposit has gone on for a long time and the solution not 

 been agitated, so that it has become very much exhausted of silver 

 round the article, the deposit towards the end of the time has been 

 almost impalpable to the touch, like flour : sometimes the grains 

 were a little coarser. The practice, in such cases, is to lift the 

 articles from the solution, and to place them in boiling water, and 

 after steeping there some time, to take them out, when the heat of 

 the metal soon causes it to dry. Under these circumstances, when 

 the deposit was of the sort stated, we have seen on a large waiter or 

 tray, when the hand was rapidly drawn over the surface, after it was 

 dried in the manner described, the same effect produced as when 

 the hand is drawn over an electrified handkerchief, or sheet of 

 paper, accompanied with a crackling noise and pricking sensation. 

 We have repeatedly observed these phenomena, but never having 

 chanced to be in the dark, no light was visible from the surface 

 rubbed. Although these are the conditions under which the obser- 

 vations were made, the phenomena were not produced every time 

 these conditions were found. It is probably caused by the fact that 

 this kind of deposit, which is of a chalky appearance, is a bad con- 

 ductor of electricity, and as the boiling water was often very impure, 

 holding salts in solution, the rapid evaporation of the water from the 

 surface of this sort of deposit might leave it excited for a short time, 

 and the hand being drawn across at the time of excitation, the elec- 

 tricity was liberated. 



The old method of Plating Many objections have been urged 



against the application of electro- deposition to the purposes of 

 plating, as a branch of manufacture, either as a competitor or sub- 

 stitute for the old method, technically called Sheffield plate so 

 called because Sheffield is a principal seat of that manufacture. 

 To enable our readers to form a proper estimate of the objections 

 urged, by enabling them to judge of the relative importance and 

 value of the two processes, we shall add a brief description of the 

 old method. 



An ingot of copper being cast, was filed square and smooth, and 

 a piece of silver was placed upon it, the two surfaces being perfectly 

 clean : a little borax having been introduced between the two 

 metals, they were bound together with iron wire, and then heated 

 in a furnace nearly to the melting point ; the small quantity of 

 borax increased the fusibility of the two meltals at their surface, and 



