424 ETCHING. 



scratches made by the pumice-stone ; and it is then 

 finished with a piece of charcoal of a finer grain, 

 with a little oil. 



Etching-points or needles are pointed instruments 

 of steel, about an inch long, fixed in handles of 

 hard wood, about six inches in length, and of the 

 size of a goose-quill. They should be well tem- 

 pered, and very accurately fixed in the centre of 

 the handle. They must be brought to an accu- 

 rately conical point, by rubbing upon an oil-stone, 

 with which it is also very necessary to be provided. 

 Several of these points will be necessary. 



A parallel-ruler is necessary for drawing parallel 

 straight lines with. This is best when faced with 

 brass, as it is not then so liable to be bruised by 

 accident, 



Compasses are useful for striking circles and 

 measuring distances. 



Aqua fortis, or what is better, spirits of nitre, 

 (nitrous acid,) is used for corroding the copper, or 

 biting-in, as it is called. This must be kept in a 

 bottle with a glass stopple, for its fumes destroy 

 corks. A stopple made of wax will serve as a sub- 

 stitute, or a cork well covered with wax. 



Bordering-wax, for surrounding the margin of 

 the copper-plate when the aqua fortis is pouring 

 on. This may be bought ready prepared, but it 

 may be made as follows. 



Take one-third of bees-wax to two-thirds of 

 pitch ; melt them in an iron ladle, and pour them, 

 when melted, into water lukewarm ; then mould it 

 with your hand till it is thoroughly incorporated, 

 and all the water squeezed out. Form it into rolls 

 of convenient size. 



Turpentine varnish is used for covering the cop- 

 per-plate with, in any part where you do not wish 



