Dr Jones on Polishing Ivory ^ d^c. 141 



tides clean from rust or other oxide, by pickling them, or put- 

 ting thera into sulphuric, muriatic, or nitric acid, diluted with 

 water, as usual, and washing them well afterwards in water, he 

 put them into a stoneware gallon bottle, having an oval body, a 

 narrow neck, and a handle to lift it by, together with a propor- 

 tionate quantity of bar or grain tin, and of sal ammoniac. He 

 then placed the vessel, lying upon its side, over a charcoal fire, 

 made upon a forge-hearth, and heated it ; continually tqrning 

 it round all the while, and frequently shaking it, to distribute 

 the tin uniformly over the surfaces of the articles to be tinned. 

 They were then thrown into water, to wash away all remains of 

 the sal-ammoniaCj and finally dried in saw-dust made warm. 



The great merit of this process consists in the employment of 

 the stoneware vessel, which not only prevents the dissipation of 

 the sal-ammoniac in fumes ; but also gives up the whole of the 

 tin to the articles to be tinned, which would not be the case 

 were a metallic vessel to be used. 



On polishifig Ivory ^ Bone, Horn and Tortoise-shell. By Dr 

 Thomas P. Jones. 



Ivory and Bone, either plain or ornamented. 



JLvoRY or bone articles admit of being turned very smooth, 

 or, when filed, may afterwards be scraped in the manner to be 

 presently described, so as to present a good surface. They 

 may be polished by rubbing them first with fine glass paper, 

 and then with a piece of wet linen cloth dipped in powdered 

 pumice-stone ; this will give a very fine surface, and the final 

 polish may be produced by washed chalk or fine whiting, ap- 

 plied upon another piece of cloth wetted with soap suds. 



Care must be taken in this, and in every instance where arti- 

 cles of different fineness are successively used, that, previous to 

 applying a finer, every particle of a coarser material be re- 

 moved, and that the cloths be clean, and free from grittiness. 



Ornamental work must be polished with the same materials 

 as plain work, only using brushes instead of linen or woollen 

 rags, and rubbing as little as possible, otherwise the most pro- 

 minent parts will be injured. The polishing materials should 

 be washed off* with clean water, and, when dry, the articles may 

 be rubbed with a clean brush, to finish them off. 



