LANTERN SLIDES. 
155 
is run into the trough for an hour or two. And small 
glass dishes are sold for lantern-slide plates; but when 
the exposure is learned several plates may very well be 
developed in one large dish, for the development should 
not be very rapid. If a bromide plate develops with 
ferrous oxalate in less than three or four minutes it will 
probably be found to have a greenish tone, which is a 
sure sign of over-exposure. 
The Metol Developer may be used for this work; 
the solution as formulated on page 120 must not be 
diluted, and exposure must be kept down, but bromide 
may be added to the developer without impairing the 
tone of the resulting slide. The blacks obtained with 
metol are of a somewhat warmer character than with 
ferrous oxalate. Another developer well worthy of trial, 
because it seems almost incapable of fogging a plate, is 
the Glycin of Messrs. Hauff. It may be made up as 
follows : 
Glycin ... ... ... 5 parts or 75 grains. 
Potass, carbonate ... .. 20 ,, or 300 ,, 
bodium sulphite ... ... 20 ,, 300 ,, 
Water to ... ... ... 100 ,, 3 ounces. 
For use dilute one part of this to three parts with 
water. This developer ought to act very slowly if the 
exposure has been correct ; ten minutes will not be too 
long. Here, too, bromide may be used if the develop¬ 
ment is too rapid, or the high lights show tendency to 
fog. But if the exposure has been nearly correct, no 
bromide will be required, or a very small quantity at 
the most. 
A poor lantern slide may almost always be attributed 
