MECHANICS AND USEFUL ARTS. 47 



experience ; and it is, perhaps, a good plan either to take a lesson or 

 two in grouiiu- laying, and the other parts of this process, from an 

 engraver, or else to get one of this profession to lay the ground and 

 bite in the plate when etched. 



The ground having been made ready and the plate cold, an out- 

 line of the subject, prepared on ordinary or tracing paper, should be 

 damped and transferred by means of pressure. The best way to 

 manage this is to take it to a copper-plate printer, who will do it effect- 

 ually for a few pence; for those living in the country where such 

 conveniences cannot properly be had, this transfer can be made by 

 one of the ordinary letter-copying machines, or by going very deli- 

 cately over the back of the outlines with a pencil or other instru- 

 ment which is not too sharp. 



This having been done, by means of an etching-point, which can 

 be had at the tool-maker's, the design can be readily scratched upon 

 the plate. Attention is needed to mark the lines quite through the 

 ground. The hand should also be prevented from coming in contact 

 with the ground, and all unnecessary scratches be carefully avoided. 

 This may, to a considerable extent, be done by forming a bridge of 

 a flat ruler, supported by pieces of card-board or folded paper. 



Wherever the etching-ground has been passed through by the etch- 

 ing-needle, that part is liable to be eaten into a line by the application 

 of acid ; on no other portion, however, should the acid work. 



It being necessary to cover the etching with an even depth of dilu- 

 ted acid (from a quarter to half an inch) , in order to produce equality 

 in the biting, it is needed to form a wall of wax round the margin of 

 the work. The best material for this is beeswax with a small part of 

 Burgundy-pitch added, and then the mixture boiled until the whole is 

 well mixed. This, when needed for use, should be put into warm 

 water, and then can be readily raised round the plate and pressed 

 down by the fingers, and after that more firmly by the handle of the 

 etching-point, so that a sort of tank is formed, which will contain the 

 acid as long as it may be necessary. 



With the greatest care scratches may be made, or it may be neces- 

 sary to erase parts, or the wax-wall may not be sufficiently tight. In 

 order to remedy this, turpentine-varnish, or the ordinary " Bruns- 

 wick black " used for stoves, may be employed, thinned to a proper 

 extent by turpentine, and applied with a black-lead pencil. 



For the purpose of " biting in " the plate, as the engravers call it, 

 nitric acid of the purest description should be mixed, one part 

 of acid and three parts water, which should be stirred up with a 

 feather or pencil. Soon the lines will be covered with minute glob- 

 ules ; and, in proportion to the time the acid is allowed to remain, 

 the etched lines will become thicker and deeper. 



As a matter of course, in order to produce a delicate and refined 

 effect, a variety of thicknesses of line is desirable ; and, although 

 much can be done by the pressure of the point, by hatching, doubling 

 lines, etc., it is in most cases necessary to allow the acid different times 

 of action ; for instance, it will be desirable to keep distant moun- 

 tains and landscape thin, and to bring out the foreground by bold 

 and deep lines. In order to manage this, the acid must be poured 

 off into a vessel for further use, and then the plate must be well 



