THE YOUNG SCIENTIST. 
119 
Burnished Gilding on Glass. 
IN the first place, it is necessary to imike 
a size for fixing tlie gold leaf to the 
glass, which is made in the following 
manner : Obtain some best isinglass, and 
place as much in a teacup as will cover a 
shilling piece; then pour half a cupful 
of boiling water upon it; then add as 
much spirits of wine as water in tlie cup, 
strain the whole through a piece of fine 
cambric or a silk liandnercliief ; when 
cold it is ready for use. Whatever writing 
or ornament you require to put on the 
glass must be first drawn or set on paper 
the exact size of the glass. When you 
iiave made your design or letters on the 
Xjaper (with a lead pencil) the size you re- 
quir :, prick the outlines through with a 
fine needle, placing the paper on a piece 
of smooth, soft wood, so that it does not 
blunt the point of the needle (and make 
the holes unnecessarily large). When 
this is done, clean your glass thoroughly ; 
then place your design, reversed, to back 
of the side you mean gilding, fixing it 
with a little gum at each corner; then 
place your glass in a slanting position. 
Take a large size swan-quill pencil, and 
flow the size on where you require the 
writing or ornaments: then commence 
gilding, putting your gold out on a 
cushion, and cutting it the ])roi)er sizes, 
or of such sizes as you can easily take up 
with the tip. Let each joint overlap the 
otlier, gilding the whole space where the 
writing, etc., is to be, having the gold 
about one-fourth inch wider at the toj) 
and bottom of the letters. When you 
have completed the gilding so far, the 
glass should be set upright to drain the 
surplus size off, and near a fire, or in a 
warm place, to dry. When dry, which 
you will ascertain by its assuming a bur- 
nished appearance, take a piece of cotton 
wool and rub it over very softly. By this 
means you will remove all the loose pieces 
of gold, and increase the burnish of the 
gold. If there are any faulty places in 
the gilding, flow a little size on the place, 
and put a piece of gold over it, rubbing 
the place so repaired gently with cotton 
wool, when dry. Then use a large flat 
camel-hail- brush, and size the whole of 
the gold over lightly, so as not to disturb 
the gold. When this is dry, pour some 
hot water over the gilding, which en- 
hances the brilliancy of the gold very con- 
siderably. When dry, which it will do in 
a very few minutes, size it over softly to 
prevent the paint from percolating the 
gold. Having completed your gilding, 
you take your design off the back of the 
glass (which enabled you to see how far 
to gild), and place it on the gilded side, 
reversed, taking care to fix it securely, so 
that it shall not move, while you pounce 
it over with a white pounce softly ; then 
raise the paper off the glass carefully, so 
as not to brush the pounce marks away. 
You will then have the outlines of your 
design left on the gold. Take a sable 
writing pencil, and fill up the outlines 
with Brunswick black of as tlnck consis- 
tency as you can work it with the pencil ; 
when this process is (piite hard, take a 
wet sponge, and gently wash all surplus 
gold off clean. Then take a small straight- 
edge and a chisel, and cut the top and bot- 
tom of the letters, etc., quite straiglit and 
true. This process is called trimming, by 
which means you obtain a sharx^ness of 
outline that you could not obtain with the 
pencil, however expert you may be. You 
may then shade in what color you think 
proper, and x)aint whatever color back- 
ground over all to suit your fancy,— Df?- 
slgii and JVo7'k. 
Instantaneous Photography. 
WHEN objects are in rapid motion it is 
very difficult to observe them dis- 
tinctly. This does not arise from the fact 
that the eye fails to get an impression of 
the object, because it can be proved that 
objects may be distinctly seen even when 
presented to the eye for less than the 
one-thousandth part of a second. But 
owing to what is known as the persist- 
ence of vision, objects in motion give rise 
to a series of images on the retina, and 
as these images overlap, as it were, the 
result is a confused blur. The best illus- 
tration of this is seen in a common experi- 
ment well known to every boy and girl. 
Take a stick with the end on fire and 
glowing, and move it slowly either back 
