ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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(3) Mix ono fluid dram of alcohol, 95 per cent., into a fluid dram 
of sulphuric ether; pour into the gelatin and mix well. If too thick, 
thin it with acetic acid to suit, and add 6 or 7 drops of glycerin 
(C. P.) ; mix the whole thoroughly with a clean stick. 
Do not insert the cork or shake the bottle with the ether and 
alcohol in it, or it will generate sufiBcient vapour to burst the glass 
or blow the cork out with half the cement. When it gets too thick in a 
warm room through evaporation, thin with alcoholic; ether if you want it 
to dry faster; or with acetic acid to dry slowly. 
Try it on glass, and if too brittle or liable to crack, add more glycerin, 
say two drops at a time, mixing well and repeat if necessary, until the 
cement will dry hard in from two to five hours; if at the end of two 
weeks (in a warm room) it will bear the test referred to above, it is suf- 
ficiently hard for filling up around balsam mounts, which have become 
hard and solid ; for labels it has no equal. 
Pour some of this cement into a 1 dram phial and colour it suffici- 
ently with a strong solution of black ‘ Diamond ’ dye, and you have a 
beautiful black cement. With Diamond dyes you can give it any 
colour. In this case, the acid must be left out as it will precipitate the 
dyes and spoil the beauty of the cement. Alcohol, 50 per cent., will 
have to be used in lieu of the acid, and the mixture placed in warm water, 
if too cold or thick. 
By mixing plenty of moist Chinese white with the colourless 
cement, and grinding it thoroughly in a mortar and placing it in a 
bottle with a sufficient quantity of glycerin to prevent cracking, you 
will have a beautiful and durable white cement. On a fair trial it 
will be found that these cements will have no equal for durability 
and tenacity on glass, and that they will not run into balsam mounts 
if the latter are sufficiently hard for any cement whicli dries quickly. 
It will be necessary to give the rings made of these cements several 
coats of amber varnish or the best copal varnish, so as to resist 
moisture. I do not recommend these coloured cements for aqueous 
mounts lest they run in. Balsam, gelatin, or gum mounts, when neatly 
finished with the following transparent cements, are unequalled in 
beauty, and probably as durable as any ; they never ruin any mounts 
by running in, and save the time consumed in ornamenting, which 
really adds no essential value to slides. Procure a good colourless 
amber, or best colourless copal varuisb, and add a little white beeswax 
to one bottle of amber or of copal varnish or palmitate of alumina* 
instead of wax, and it will increase the tenacity and elasticity of the 
cements which are to be used for the body of the ring around moist or 
aqueous mounts, while the last, or last two coats, should be as hard as 
possible ; they will adhere to softer coatings, while they might bo too 
brittle to apply directly to the glass. 
Good gold size has only one fault, it dries too slowly. The best 
copal varnishes are just as good, and dry in much less time. I abhor 
all fluid mounts, and therefore have no use for that miserable, brittle, 
crumbling white zinc cement which soon assumes a dirty mud colour. 
When glass can be prepared to inclose an object in fluid and be 
as durable as the cells or tubes of spirit-levels, or bulbs of thermometers, 
* Dissolve in oil of turpentine. 
