■7? 



DEFINITION OF TEKMS. 



The mode of preparing this color is 

 kept from the public. It is said to be ex- 

 tracted from cochineal by means of water 

 wherein chovan and antour have been in- 

 fused; some add rocoLi but this gives it too 

 much of the opal cast. 



Others make carmine of Brazil wood, 

 ferncmbouc, and leaf gold beaten in a mor- 

 tar, and steeped in white wine vinegar; 

 the scum arising from this mixture, upon 

 boiling when dried, makes carmine; but 

 this kind is vastly inferior to the former. 

 There is another carmine, made of Brazil 

 wood and fernembouc, by a different pre- 

 paration. 



Carton or Cartoon — In painting, a 

 design drawn on strong paper to be after- 

 wards calked through, and transferred on 

 the fresh plaster of a wall to be painted in 

 fresco. Carton is also used for a design 

 colored for working in Mosaic, Tapestry 



Case Hardemn<i — A method of pre- 

 paring iron or steel so as to render its outer 

 surface hard, and capable of resisting any 

 edge tool. The follovving is Mr. Perkin's 

 method. The article is exposed to a red 

 heat for three hours in a cast iron box, sur- 

 rounded with a powder made of equal 

 parts of burned bones and the cinders of 

 burned animal matter, such as old leather, 

 and then plunging it slowly while hot into 

 cold water (previously boiled to deprive 

 it of air) to the depth of three or four feet, 

 and leaving it there till cold; by which 

 means it acquires hardness without danger 

 of springing or cracking. 



It may afterwards be tempei'ed by heat- 

 ing it in oil heated to 460 degrees in melt- 

 ing lead or in a thick mass of cast iron — 

 till the required hardness is obtained which 

 13 shown by the color on a part previously 

 polished with an oil stone. 



Casting — Among sculptors, implies the 

 taking of casts and impressions of figures, 

 busts, medals, 4'C. 



Medals of isinglass may be formed in 

 the following manner; dissolve isinglass 

 in water over the fire, then with a hair 

 pencil, lay the melted isinglass over the 

 medal; and when you have covered it pro- 

 perly let it dry. When it is hard, raise 

 the isinglass up with the point of a pen- 

 knife, and it will fly ofi^ like horn, having 

 a sharp impression of the medal. 



The isinglass may be made of any color 



by mixing the color with it; or you may 

 breathe on the concave side, and lay gold 

 leaf on it, which by shining through will 

 make it appear like a gold medal. But if 

 you wish to imitate a copper medal, mix 

 a little carmine with the isinglass, and lay 

 gold leaf on as before. 



Calenaria — The name of a curve line 

 formed by a rope hanging freely from two 

 points of suspension whether the points 

 be horizontal or not. 



A rope suspended from two points, in 

 horizontal positions from each other will 

 form a curve, which reversed is a form re- 

 commended for the arch of a bridge, where 

 each part is intended to support an equal 

 weight; but where a greater weight is in- 

 tended to rest upon one part than another, 

 the proper curve may be produced by sus- 

 pending at each respective part of the 

 rope, a body of the same relative as that to 

 be supported by the arch directly over it 

 when the curve is reversed. 



Ctrnent — Any glutinous substance ca- 

 pable of uniting and keeping things to- 

 gether by cohesion. The following are 

 some of the best compositions used for 

 the purpose of cementing together various 

 articles. — 



Jewelers Cement — For setting precious 

 stones when pieces are broken off by ac- 

 cident. The fragments are heated and a 

 small piece of gum mastich is applied be- 

 tween them, and the parts forced together 

 until a portion of the redundant melted 

 gum is forced out. 



Turkey Cement ^ for joining metuls, 

 glass, 4'C. — Dissolve ^mastich in a quan- 

 tity of spirits of wine that will render it 

 liquid; in another vessel dissolve as much 

 isinglass, (ivhich has previously been soak- 

 ed in water till it is swollen and soft,) in 

 brandy or rum, as will make two ounces 

 b}' measure of strong glue, and add two 

 small bits of gum galbanum, or ammoni- 

 cum wbich must be rubbed or ground till 

 they are dissolved, then mix the whole 

 with a sufficient heat, keep it in a phial 

 stopped, and when it is to be used set it in 

 hot water. 



Centrifugal force — that force by which 

 all bodies that move round any other body 

 in a curve endeavour to fly off from the 

 axis of their motion in a tangent to the 

 periphery of the curve, and that in every 

 point of it. 



