1875.| The Spectroscope in Mint Assaying. 83 
the gold lines were strong and bright, while in the section 
representing the base alloy the gold lines were very faint. 
(Fig. 2.) 
By now gradually increasing the distance between the 
electrodes, the faint gold lines of the base alloy cease to 
join their bright counterparts of the fine metal at the central 
line. (Fig. 3.) 
The intervening space is at first minute, but as the elec- 
trodes are further separated, the ends of the faint lines 
gradually recede towards the outer edge of the spectrum, 
until they finally disappear altogether. 
The general principle was thus satisfactorily proved, that 
where two alloys of different grades are subjected to this 
treatment, the gold lines of the baser compound are notice- 
ably the fainter of the two, and, what is more important, 
they may be reduced in length by separating the poles, until 
they disappear. 
This pointed to the possibility of the future application of 
spectrum analysis to assaying, at least, as a test method. 
For, if an alloy of absolute known fineness were adopted as 
one electrode, and an ingot-slip assayed by the old process 
to an equal grade of fineness were inserted as the opposite 
electrode, in case the assay were correct, the gold lines in 
