MOUNTING OBJECTS ‘‘OPAQUE” IN BALSAM. 197 
bank of mud and vegetable deposits which had formed the subject 
of the paper. He also referred to the finding of the Teal’s egg in 
the decayed rushes, with the feathers from the bird surrounding it, 
and the yolk of the egg which was found (after its shell had been 
broken) in a somewhat petrified condition. Major Davis thought 
it impossible that the tide had ever reached the city since the 
Roman occupation, as he was able to prove that the present level 
of the city was even lower than in its Roman history. He 
suggested that it might be possible for the shells to have been 
washed down from the neighbouring hills to the site they at present 
occupied. 
MOUNTING OBJECTS “OPAQUE” IN BALSAM. 
By E. Warp, F.R.M.S. 
LL those who, being interested in the Microscope, are also 
preparers of their own slides will probably have noted, that 
there are some few objects which, although too opaque for trans- 
mitted light, are yet more beautiful, if mounted in Balsam, than 
when dry. ‘This is most apparent in the various parts of some 
diamond beetles, such as the genera of Entimus and Cyphus. 
In the old days, when paper-covered slides were much in vogue, 
this kind of preparation was readily made, it being only necessary 
to paint the slide at the back with Black varnish, which was 
protected by the covering paper; but when it was seen how much 
better appearance the slides presented if uncovered, but neatly 
ringed, it was found a more difficult matter to get this same opacity 
for Balsam Mounts as, if the opaque varnish was placed inside the 
cell, it was frequently dissolved by the Balsam, and if painted on 
the under side, it almost always became unsightly through being 
rubbed, offending those who care for the neatness of finish of their 
slides. 
I succeeded some months since in producing a Black which 
could be used with safety under the cell, and having given it plenty 
of trial, I bring it before you to-night; the process being moder- 
ately easy, and the materials to the hands of almost every worker. 
Having affixed to the glass slip by means of Brown cement, a 
metal cell of sufficient depth (and it is absolutely necessary that it 
be quite as deep as the object to be mounted, or the after process 
will be more difficult), allow this to dry, and then paint the inside 
of the cell on the glass with a Black varnish made by adding lamp- 
black to Brown cement. This Black varnish should only be made 
as required, and for a small quantity it is only necessary to put a 
