AMALGAMS FOR STOPPING TEETH. 
265 
a.,piece of zinc is immersed. In the course of two or three 
days (according to the quantity submitted,) all the silver 
will be reduced to the metallic state ; you then remove the 
zinc. To ascertain the weight of silver you have to amal- 
gamate, it is necessary to weigh the piece of zinc before 
submitting it to the paste, and the loss of weight which the 
zinc sustains will be equivalent to the weight of metallic 
silver produced. To this may be added six or eight times 
its weight of pure mercury, which must be triturated in a 
mortar, with warm water for several hours, or so long as the 
mass continues in the least to discolor the water. The 
operator will discover the pasty adhesiveness which the 
amalgam will require as he proceeds ; and for this part of 
the process it is better to have an excess of mercury, which 
can be squeezed out, and should leave, at the conclusion of 
the operation, an amalgam composed of one part of silver 
and four parts of mercury. This amalgam of silver is to be 
united with an amalgam of gold. 
The amalgam of gold may be prepared by putting 
ribbons of pure gold (similar in thickness to that which 
gold beaters commence beating with) into heated, or nearly 
boiling, pure mercury, and in the proportion of four mer- 
cury to one gold. This may be poured into a mortar con- 
taining water, and washed, as the silver amalgam, so long 
as the least discoloration appears in the water. This should 
be freed of its superfluous mercury, and the mass should 
consist of gold one part, mercury three parts. 
It may be well to observe, that these amalgams retain a 
little water in the interstices of the mass ; and to prevent any 
displacement from the spoon in after use, it is well to dry 
them, by gently rubbing them with a soft towel, or upon 
bibulous paper. 
The amalgams being now perfectly pure, it may be well 
to keep in separate boxes the little pellets necessary for 
combination of the compounds; and the proportions are 
two parts by weight of the gold amalgam to one of silver. 
I have found it to become a more compact mass by the 
