840 - General Notes. | December, 
If common curtain rings are fastened to slides with shellac 
cement, colored with aniline blue, the joined edges of the brass 
film of which the ring is made being on the glass, and then sub- 
jected to a slowly increasing heat until the cement begins to burn, 
a very beautiful ornamentation is given to the under side of the 
ring, a circle of minute golden links making their appearance 
there. These rings can then be painted according to fancy on 
the turn-table and used for any kind of mounting. 
I use this cement, colored with the various aniline dyes which 
are soluble in alcohol, for painting and finishing slides. These 
colors are far superior, for all purposes of ornamentation, to any 
other material or devices for painting; they dry quickly and 
adhere to glass with greater tenacity than any other cements 
that I have ever used. 
For a cell that will perfectly withstand the action of Canada 
balsam or turpentine, I make use of the shellac cement colored 
with aniline blue, in the following manner: After a cell of the 
required depth is made on the slide and pretty thoroughly dried 
in the usual way, it is heated on the heating table, slightly at first 
in order to. avoid bubbles, then’ gradually increasing the heat 
until the cement commences to smoke and the color to burn out. 
By heating one side of the ring a very little more than the other, 
as may be done over an alcohol lamp, a part may be left blue 
while the other is yellow or reddish, which has a very pretty 
effect under Canada balsam. These cells are hard as bone, and 
can scarcely be cut from the glass. Balsam has no effect what- 
ever on them. Mountings on them may be finished off with 
liquid balsam, made true and circular with the point of a knife on 
the turn-table. In a few days, or ina shorter time by using the 
oven, they will be ready to clean and lay away. The cells which 
I have described are the only cement cells that can be used with 
Canada balsam. They are particularly adapted to vegetable 
stainings, alge, and all other preparations either too thick or too 
tender to be mounted in balsam without something to sustain the 
thin glass covers. 
In opaque mountings when cements of any kind are used, 
either for back-ground or to hold the object in place, I have 
found it highly advantageous to leave on, or in the lower part of 
the ring, a minute aperture opening into the cell, not necessarily 
_ larger than a cambric needle would make. With this provision both 
the cell and the cement go on drying, and there is no sinking in 
or moving about of the objects in the medium which holds them. 
If the cell be hermetically closed, one may expect that the object 
will, sooner or later, be overwhelmed in a black sea. If curtain 
~ rings are used, a little notch can be filed in the side of them, and 
_ this be left open when the slide is finished. i 
= H the opaque mountings are for dry objects, I make in the 
center of the ring a disk of Brunswick black or white zinc, accord- 
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