THE YOUNG SCIENTIST. 
73 
The first preparatory process is laying 
the etching-ground. 
The plate having been polished from 
tarnish, in order to remove all grease 
from the surface, wash it well with spirit 
of turpentine, and, after the plate is dry, 
rub it carefully with whiting and wash- 
leather ; then fix the hand-vice, and pro- 
ceed to heat the plate either on the top of 
a stove, or by any other process by which 
a steady and not too great a heat may be 
obtained; in the absence of a stove, a 
piece of flat metal, heated and placed on 
bricks, is a good substitute. It may be 
known when the plate is sufficiently hot, 
by placing the etching-ground on the 
plate with a gentle pressure, and, after 
allowing it to remain a few seconds, pass 
it slowly from one end of the plate to the 
other ; if a thin layer is equally left along 
the surface, the heat is proper. Continue 
to pass thin layers of etching-ground from 
end to end of the plate^ at tolerably equal 
distances, and then, in the same manner, 
from side to side ; the object of this is to 
place an equal quantity of etching-ground, 
in order that the dabber may spread it 
more readily over the surface ; then take 
the dabber (Fig. 6), now in requisition, 
and use it by constantly dabbing over the 
plate for the purpose of entirely covering 
the portion of the plate required. When 
an even and complete layer has been ob- 
tained, take a v»rax-tai3er (Fig. 7), and 
next proceed immediately to smoke the 
ground; the taper must be kept in 
motion, in order that the whole of the 
ground may be evenly blacked; if the 
flame of the taper is allowed to remain 
too long in the same position, the ground 
will be burnt, and not offer sufficient re- 
sistance to the acid; and if the plate, 
during the process of smoking, is too 
cold, the smoke will not incorporate itself 
with the ground, but remain on the sur- 
face. The essentials of a good ground 
are, first, that the surface be comjMely 
covered; second, the covering to be as 
equal as possible, and not so thick as to 
prevent the free use of the etching point ; 
and third, that it shall present, when cold, 
a polished black surface. If, when the 
plate is cold, the surface appears in i)arts 
dull, it is caused either by the ground 
being burnt by using too much heat 
while spreading the ground, or that, when 
smoking, the plate has been too cold. It 
is easy, when the plate is cold, to discover 
from which of these causes the dulness of 
the surface proceeds, by rubbing the part 
slightly with a soft handkerchief ; if the 
black is removed to the handkerchief, the 
plate has been too cold when the taper 
was api)lied ; but if the dull black remains 
on the plate, the imperfection has been 
caused by heat. If the dulness arises 
from the smoke lying on the surface, it 
may be readily altered by slightly heating 
the plate ; if from burning, the ground 
must be removed by heat and spirit of tur- 
pentine, and the plate again thoroughly 
cleansed. 
The best method of getting the subject 
transferred to the plate is to send a careful 
outline, either in pencil or red chalk, to 
a copperplate-printer, who will slightly 
damp and pass it through the press. If 
this is not convenient, a piece of tissue 
paper may be rubbed with powdered Ver- 
million, and fixed with the colored side 
towards the plate. The tracing must then 
be put in its proper place, and fastened 
with wax at the corners to prevent it shift- 
ing. The outline must be then gone over 
with a blunt etching-point. This process 
will leave a clear outline in red, on a black 
ground. When thus transferring, the 
pressure should not be so strong as to 
damage the etching-ground. 
The student will observe that, in order 
that the plate may throw off a correct im- 
pression, the subject must be reversed. 
This difficulty may be remedied by plac- 
ing the drawing so that it may be seen in 
a looking-glass, which will have the 
effect of giving it the same appearance 
that it would have on the plate. 
The plate is now prepared for the etch- 
ing process. 
A New Breed of Whales.— A whaling 
captain, lately returned from the Arctic 
seas, declares that a new breed of whales 
have made their appearance in those 
waters. They are supposed to have 
emigrated from the open sea at the 
Poles. 
