344 - GILDING. 



Annotation. 



Though the indistinct outline of a large object not deeply 

 immersed in a small stagnant pool, may seem to be well ex- 

 plained by the observations given at page 304, of our XXXIVth 

 vol. Yet the same principles do not appear adequate to shew 

 why the ramifications of a tree buried twenty feet in a bog, 

 should be neatly figured upon the ice of water lying on its sur- 

 face. None of the general operative powers with which we 

 are acquainted, present a solution of thiseffect. Heat, electri- 

 city, gravitation. Of these the latter only is known to act in 

 the perpendicular ; but this affords no ground for the remotest 

 conjecture. It would be desirable to know whether the ice of 

 the outline were different in texture from the rest. — W.N. 



V. 



On Copper Wire, guilt with Brass. In a Letter from a Cor- 

 respondent. 



To Mr. Nicholson. 

 SIR, 



I HAVE been informed, that the gilding of copper wire by 

 means of brass is carried to great perfection in Germany. 

 Perhaps it may also be the case in England j respecting which I 

 should be glad to hear from your correspondents. The facts, 

 as stated to me, are, that copper wire, coated with brass, is ca- 

 pable of being drawn out to the fineness of a hair j much finer 

 than copper alone -, that it is used for making gold lace, 

 and the process effected in the humid way, as follows : — Take 

 of zinc one part, and of mercury twelve parts — make a smooth 

 soft amalgam, to which, if a little gold be added, it will be 

 better. Clean the copper very nicely with nitric acid - f put 

 the amalgam into muriatic acid, and add argol or crude (not 

 purified) tartar. Boil the clean copper in this, and it will be 

 very finely gilt. Epaulets and gold-coloured trinkets are thus 

 made very beautiful. 



Query. Would this be an improvement in pins ? 

 I am, Sir, 



Your Constant Reader, 



M.M.B. 



