138 



ELECTROLYSIS. 



per minute, and is used for the polishing of plane surfaces. The 

 ends of the spindles of the machines / are screw-shaped, so as 

 to receive brushes, small disks, and generally all the polishers 

 of small diameters used for the preparation of the pieces having 

 deep recesses. The spindle rotates at 3200 revolutions per 

 minute. 



The machine h (Fig. 25) which is commonly called the 

 special polishing machine, consists of an endless leather band, 

 sprinkled with emery, and which can be stretched more or less 

 by means of a screw and handle. The benzine table i is a table 

 lined with zinc and having a raised border so as to gather the 

 benzine which may be upset during the working. 



FIG. 26. 



Oven for Drying the Nickel-plated pieces. 



The oven g, which is entirely built of sheet iron (Fig. 26), 

 is used for drying the nickeled pieces and removing the benzine 

 which remains attached to them notwithstanding their passage 



