THE YOUNG SCIENTIST. 
83 
are able to make either one or both of 
these articles." 
This pleased the boys, and they imme- 
diately persuaded their father to assist 
Fig. 41. 
them to make the articles, and to pur- 
chase materials for them. 
The engraving, Fig. 41, shows a design 
of an umbrella stand the boys decided 
to make. In our next paper we will see 
how they prepared their stuff and put the 
work together. 

Etching on Copper— II. 
WHEN etching, care must be taken to 
prevent any grease from coming into 
contact with the etching-ground; and it 
is proper to fix pieces of thin wood or 
folded paper round the edge of the plate, 
in order, with the help of a ruler, to form 
a sort of bridge on w^hich to rest the hand. 
This precaution is necessary in order to 
protect the ground from scratches. These 
supports may be fastened with bordering 
wax. The etching-point is used in a simi- 
lar manner to a blacklead-pencil ; and it 
is very important to bring it into good 
working condition by rubbing it on a hone 
or leather strop. The point ought to be 
of such a degree of sharpness as to move 
freely on the plate ; at the same time it is 
necessary that each line should go com- 
pletely through the ground, otherwise the 
etching, after biting, will present a very 
rotten appearance. 
Wax is now used for the purpose of 
forming a wall round the plate of about 
an inch high to confine the acid; it is 
composed of beeswax and Burgundy pitch, 
in the proportion of one pound of bees- 
wax and a quarter of a pound of Bur- 
gundy pitch. The ingredients must be 
chopped into small pieces, and allowed to 
boil slowly in an earthen pipkin. As soon 
as the whole is dissolved, it is necessary 
to pour it into a basin partly full of warm 
water; it must then be worked by the 
hands until it becomes a pliable substance 
similar to shoemaker's wax. When using 
the bordering wax, it may be placed in 
hot water for the purpose of rendering it 
more workable, and it is necessary to be 
very careful to press it closely to the plate 
in order to prevent the acid from escaping 
(Fig. 8). It is also better to varnish round 
Fig. 8. 
the inside of the wax with great care, lest 
the ground underneath the wax may have 
been removed. If not thus protected, the 
margin will be filled with holes, which are 
troublesome to remove. 
Fig. 9. 
It is difficult to give any precise direc- 
tions for biting, as much depends on the 
