OO a ae ee - 
A. H. Chester—Artificial Crystals of Gold. 31 
smallest angle noticed was 80° 36’. The following table of sev- 
eral consecutive measurements shows how wide the variation 
is, the last column giving the total angle between the sets of 
ribs. 
30° 36’ 89° 30’ 120° 6’ 
41° 54’ 73°18! 120° 12’ 
46° 48’ 73° 48’ 120° 36’ 
35° 36’ 84° 24’ 120° 0’ 
53° 42’ 64° 48’ 118° 30’ 
49° 0’ 73° 36’ 122° 36’ 
38° 0’ 81° 6’ 119° 6’ 
49° 42’ 69° 54’ 119° 36’ 
It is noticeable that the same angles ers carried out in each 
crystal, no matter how many branches it may have, sigh the 
crystal shown in fig. 2 was selected to iaeeome this fac 
I have been quite surprised that no trace of faces is | to be 
observed upon these crystals, as is always the case with natural 
ones. The latter are seen under a low power to be made up of 
strings of distorted isometric crystals which are often so dis- 
tinct that they can be measured. The artificial ones do not 
show this structure, and when magnified to 300 diameters only 
show a slightl beaded look along the side ribs, but nothing that 
can be Sa distinct crystalline forms. With the power 
anil the whole surface of each crystal is in focus at once, 
ering that the different sets of ribs are in the same plane. 
Fig. 2, with all its branches, was drawn complete without alter- 
ing the focus of the instrument, Where one ¢ stal lies ‘upon 
another, when examined under a power of 150 di 
are in focus at once, showing that they are exceedingly thin 
and lie perfectly flat. The power above peatone 300 diame- 
ters, is the highest with which I have examined them. Possi- 
ss with a higher power they might be ris and show 
what is their crystalline form. That they are isometric there 
is no 
If a film of amalgam is allowed to form on the surface of a 
network of indistinct crystals remaining. To accomplish this 
the gold should be perfectly pure, and the heat applied very 
gently at first. With the greatest pains, however, the result i is 
not always, or even often, satisfactory. The surface is gener- 
ally left in an amorphous condisony or at best covered wi 
men sesh may pit be naa if the pabeli is dis- 
solved out with athete aise acid, instead of beieas driven of: by 
