PHOTOMICROGRAPHS AND LANTERN SLIDES 
157 
Ordinarily, if it is possible to do so, we believe it is better to make 
a new, correctly exposed negative or lantern slide rather than to 
reduce or intensify an incorrectly exposed one. 
Intensifying Underexposed Negatives and Lantern Slides. —Even 
if a negative or lantern slide has been considerably overexposed, 
it can be reduced quite satisfactorily; if much underexposed, little 
can be done for it; if only slightly underexposed, it may be greatly 
improved by the following solution: 
Metric 
Apothecaries’ 
1 
f Bichloride of mercury. 
2g. 
( 31 gr.) 
A 
Water. 
100 c.c. 
( 4 oz.) 
1 
1 Bromide of potassium. 
2g. 
( 31 gr.) 
B J 
f Sulphite of soda crystals. 
10 g. 
(154 gr.) 
[ Water. 
100 c.c. 
( 4 oz.) 
The solutions keep indefinitely and 
may be 
used three 
times. 
Apply the intensifier after fixing in hypo and washing in water. 
If the negative or slide has been allowed to dry, soak it in water for 
half an hour before intensifying. 
Place the negative or slide in A, rocking the tray as in developing, 
until it becomes gray or even white. Wash in water for 1 minute 
and then transfer to B and leave until the dark color can be seen on 
the back of the negative or slide. Wash in water as thoroughly as 
after fixing in hypo. 
Some use a saturated aqueous solution of the bichloride of mer¬ 
cury, without the bromide of potassium; and, instead of solution B, 
use water to which ammonia has been added—about 1 part ammonia 
to 40 parts water. Excellent sepia tones may be secured in this way. 
Wash well in water. 
After the plate has been thoroughly washed in water, wipe it 
gently with a tuft of cotton. The cotton must, of course, be thor¬ 
oughly wet; it is better to hold the plate under a stream of water 
while wiping. This should always he done before placing a negative or 
slide in the rack to dry, after a washing in water. 
Toning Lantern Slides. —A lantern slide may sometimes be made 
more effective by judicious toning. The hints given here merely 
introduce the student to the possibilities of the subject. 
Light Sepia to Red Tones. —Overexpose up to four or five times 
the length of exposure for a normal slide in black and white; develop 
