220 H. Wurtz on Sodium Amalgamation. 
tinual current of fresh water is kept running; mercurial solu- 
tions of sodium, as I have discovered, being little affected by 
5 
cases it is aguas to test the quicksilver in the rifles and 
ascertain when the magnetic quality requires restoration, by 
throwing in a few grains of gold-dust. Similar tests are easily 
applied to slimes, and in amalgamating methods generally, a slip 
of tarnished sheet copper being a very suitable agent for such 
testings. 
It may be remarked in passing, that the amalgam No. 1 is at 
a Spee easily prepared from No. 2, by melting it in an iron 
ladle with about its own weight of quicksilver, or from No. 3; 
by melting with twice its weight; considerable time, howeve?, 
being requisite, in the case of No. 8, to produce the additional 
combination. In copper-plate amalgamation, that is, in those 
cases in which auriferous materials are brought into contact with 
ated metailic surfaces, it is better to substitute altogether 
for quicksilver itself (both in the first coating of the metallic 
surfaces, and in any subsequent additions of quicksilver made) 
the pasty amalgam No.1. In these modes of amalgamation 
or slime, this water soon becomes alkaline, and ~ 
