Oct., 1890. 
PAINTING SLIDES FOR THE MICROSCOPE. 
227 
magic lantern slides. Such slides are more trouble than 
transparent ones, but they are very effective. I have seen 
some done by varnishing ordinary smooth glass with a 
resinous black varnish and scratching out the design. These 
do not look so well as mine. With a tube of Payne’s 
gray I squeeze out a little of the colour on one of my ground 
glass slides, and by means of a brush I spread it evenly all 
over the slide without using any water —the moisture of the 
colour is sufficient. This gives me a perfectly opaque slide. 
I then either let it dry gradually, or else dry it with heat and 
leave it for a few hours. It then “works” beautifully. I 
have different sized needles, from the finest possible, to 
a stout one. These are stuck in wooden handles. I also use 
the end of a wooden brush handle sharpened to a fine 
point. With these, and a knife, I scratch out my 
design. Then I paint it in the ordinary way, and finally 
finish with a fine needle. You cannot scratch off all 
the colour from the glass, and in this lies the excellence of 
my method. It makes a beautiful “half-tone ” of light, and 
the high lights are fetched up with a damp brush which 
removes all the colour. And so on the screen the pictures 
appear almost to glitter. It is because of this that I use gray 
instead of black for my background, because gray is pleasanter 
and more silvery than black for half-tones. Sepia gives a 
very nice fawn colour. Prussian blue will not do at all, 
because it chips in the scratching process, and the lines are 
ragged. If you work on a very dry day the lines will be 
rather ragged with any colour, but the paint may be moistened 
by breathing on it. If you use water in spreading the colour 
' you cannot get an opaque slide with one coat of colour ; 
and, if you varnish and put on a second coat, not only 
is this more trouble, but, when you scratch out the picture, 
the lines will be a little ragged. These dark-field slides are a 
considerable trouble to make, but they well repay one by 
being so effective. This was my first method. I prefer now 
not to make the backgrounds quite opaque, and I keep them 
moist for working on by breathing on the slide. 
Varnishing .—The painted slides as I have hitherto 
described them would not show in the lantern, because they 
are only semi-transparent; they need varnishing. Varnishing 
is by no means so easy as you might suppose, and I made 
more than 150 slides before I found out the right way. The 
friend who told me of the method of making the slides, always 
varnishes his slides with a brush, and he only varnishes what 
the colour has actually covered. Thus he gets a transparent 
picture with a semi-opaque background. Such pictures do not 
