L. TECHNOLOGY. 453 



suit is accomplished. In one instance the wood is pressed in 

 the line of its fibre in cold or slightly warmed patterns until 

 the desired relief is obtained. In the second method a metal 

 pattern is pressed very powerfully against any surface, the 

 projecting portions planed or rasped over, and the previously 

 impressed portions brought up again by wetting them in wa- 

 ter. Finally, as a third method, thin plates of wood are 

 steamed or otherwise softened, and pressed between two cor- 

 responding dies. The second method our author considers 

 of not much importance, since it requires a great deal of fin- 

 ishing oft* with the graver. The first is used to good advan- 

 tage, but it is the third which he considers worthy of especial 

 attention, since almost any form of wood can be prepared in 

 this manner, and the effect is very superior. The operation 

 should be performed with heated dies, not, however, brought 

 to such a temperature as to burn the wood. A few droj^s of 

 water placed on the dies causes a steam, which greatly facili- 

 tates the moulding of the wood. Resinous woods are not as 

 serviceable as other kinds. Shavings of wood can also be 

 used to advantage in these dies by glueing them together in 

 successive layers, each one having its fibres running j>erpen- 

 dicular to the next. In this way a mass is obtained of great 

 tenacity, and capable of being used in places exposed to moist- 

 ure, as in wainscoting. 



The so-called casting in wood may be considered as a 

 branch of the same art. This consists in taking wooden rasp- 

 ings, or fine saw-dust, especially from the pear-tree, linden, 

 and mahogany, and mixing with some sort of cementing ma- 

 terial, especially glue and tannin. These are pressed between 

 the moulds ;'ist referred to, and are capable of a great variety 

 of forms. 6 C, August 11, 319. 



PEESEEVIXG POLISHED METAL SUKFACES. 



According to Dr. Puscher, a very useful coating for pre- 

 serving untarnished the surface of polished metallic objects 

 can be made by placing an ounce of paraftine in a wide- 

 mouthed and well-stoppered glass vial, and then adding three 

 ounces of petroleum, after having melted the paraffine by dip- 

 ping the vial in boiling water. The contents of the vial are 

 then to be shaken up till the whole thickens into a kind of 

 salve. The application of this salve to polished metallic sur- 



