2. Gold Size. Boil 25 parts of linseed oil
with 1 of minium and 1⁄3rd part of umber for 3 hours; pour off the clear fluid, and mix with equal parts of powdered white lead, and yellow ochre, added in small successive portions. Then boil well the whole again, and pour off the clear fluid. It dries slowly, but firmly. Both this and the last are dissolved by turpentine.
3. Goadby’s Marine Glue. Dissolve separately in coal naphtha equal parts of shell-lac and india rubber. Mix thoroughly with heat.
4. Sealing-wax Varnish. Dissolve the best sealing-wax in enough strong spirit of wine to reduce it to the proper consistence. This is brittle.
5. Canada Balsam. This dries spontaneously.
Solutions of shell-lac, gum, and various other cements and glues are employed by microscopic manipulators.
Preservative Fluids. Canada balsam, spirit and water, glycerin, solution of gelatin, saturated solution of alum, chloride of zinc, and chloride of calcium, are all used to preserve microscopic objects.
The following formulæ will be found useful:—
1. Goadby’s Solution. Bay salt, 4 oz.; alum, 2 oz.; corrosive sublimate, 4 gr.; boiling water, 4 pints. Mix and filter. It may often be more diluted.
2. Thwaite’s Fluid. Mix spirit of wine, 1 oz., with creosote sufficient to saturate it; rub up with chalk to form a thin paste, and mix gradually with 16 oz. of water. To this may be added an equal quantity of water, saturated with camphor.