A. W. Wright—Electrical Deposition of Metals. 177 
inirror has a diameter of a little less than four centimeters, and 
both this and the smaller one, so far as the nature of the sur- 
face is concerned, appear absolutely faultless. As only com- 
mon lenses were employed in its construction the performance 
of the instrument is not remarkable, but it is sufficient 
to warrant the assurance that the method will be serviceable 
_ Many useful applications of this process may be found, and 
its use is not limited to those metals which have been men- 
tioned here. Moreover for many of them no other available 
rocess is known by which they can be deposited in a uniform 
ayer and with a brilliant reflecting surface upon glass. very 
thin layer of platinum, or still better of silver and platinum 
together, could be used with great advantage in the camera 
lucida and similar instruments. Very perfect mirrors for gal- 
