18 
Dr. Isidor Walz presented the following 
Nores ON THE EXTINCTION AND REDUCING POWER OF 
MERCURY. 
At the last meeting of the Chemical Section of the Lyceum, 
I drew attention to the conversion of liquid Zinc-Amalgam. 
to a gray powder, when shaken with a solution of Potassium 
Bichromate. Subsequently I became convinced that this phe- 
nomenon was solely due to the extinction of the Mercury, 
and have made a number of experiments regarding the 
phenomenon of which I present the following results. It is 
hardly necessary to state that the Mercury used was absolute- 
ly pure. It is very difficult, but essential, to use chemically 
pure Mercury, as even a very small trace of a foreign metal 
is often sufficient to influence the results materially. The ex- 
periments were made in ordinary test-tubes, in which the 
materials were shaken a length of time varying from a few 
seconds to 10 minutes. I believe that we ought to dis- 
tinguish between two methods or kinds of extinction, 
namely the mechanical and the chemical. The former is 
effected by a very large number of solutions of neutral salts, 
which exert no chemical action on Mercury, and even by pure 
water, if shaken long enough. The extinction of the Mer- 
cury in this case, is produced simply by the interposition of 
fine films of the liquid between the globules, into which the 
Mercury is separated by the mechanical agitation, and which 
are thus prevented from running together again. By mechan- 
ical extinction, Mercury is converted into what appears to be 
a fine powder, which, however, never loses its white color and 
metallic appearance, and under the lens its globular structure 
is clearly seen. Quite interesting in many cases, are the re- 
actions which accompany the chemical extinction of Mercury, 
which takes place when the metal is shaken with a solution 
of a salt, by which it is chemically affected. In these ¢ases, 
the newly-formed Mercury compounds act in the same way 
as the films of liquid in the former instance, preventing the 
separate globules from re-uniting. A finer division of the 
