Hep Re Phe Gy Sie 
tet ee 
2 q 
if 5 i “a 
4 eS rit Ray 
LIBRARY | ax 
cane * 4 : iy 
oo ee 
my, Fein. ay 
ys, AO oe Ba” 
pl xg Rech, 
i 
ie 
Studio and Workroom ‘ 
WEIGHTS AND MeEasureEs.—It will be noted that formulas 
in this work are usually given both in metric and duodecimal 
(or British and U. S.) weights and measures. The metric 
weights and measures are not the exact equivalents of those 
in the other systems; but the ratio of the ingredients in each 
column is the same. Readers must therefore rigidly adhere 
to one or the other system, and not weigh out solids in 
grammes and measure liquids by ounces or a hopeless muddle 
will result. In all cases the conversion has been made on the 
assumption that photographic solutions are measured and not 
weighed out and, therefore, the ratios are based on a uniform 
bulk of 16 oz. or 7680 minims. In many cases fractional 
parts have been omitted or rounded off to the nearest practical 
quantity. In all cases, too, the quantities, 1000 ccm or 16 oz., 
mean that these should be the total bulk of the solution when 
made, unless otherwise stated. Therefore, it is advisable to 
dissolve the dry ingredients in some of the solvent and then 
make up to the given bulk. 
BackGrounpDs.—Cloth is the best material, and can gener- 
ally be obtained up to 96 inches in width. Calico, bleached or 
unbleached, can be obtained up to 72 inches wide; brown felt 
paper up to 60 inches. Small pieces of cardboard, about 
Y4 inch square, are required. Lay the stretcher or frame flat 
on the floor, and get a friend to hold the right-hand bottom 
corner of the material down to the corresponding corner of 
the frame, stretch the material quite taut, and nail down the 
top left-hand corner to the edge of the frame. Drive the 
tack or nail through a piece of cardboard and the material at 
1 
