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XLIX. Question rcsbectius the lest Process for oltahiin' 

 Capper in a pure Stale. 



To Mr. Tillach. 



Sir, — A beg leave, through the medium of your publication, tb 

 request the favour of anv of your correspondents to inform me 

 of the best process for obtaining copper in a pure state, fit for 

 alloying gold, and for manufacturing delicate gold-coloured arti- 

 cles, without occasioning brittleness in tlie gold. The fine cop- 

 per employed in tlie trade for the ]>urpose of melting with gold, 

 was formerly imported from Germany, and is now not to be pro- 

 cured. The ductility of gold alloyed with tlie fine copper now- 

 kept on sale, may indeed be restored bv repeated melting and 

 hammering the alloy ; but these processes occasion loss. I, as 

 well as others, have tried the' processes recommended in the 

 most popular works on Chemistry: the gold which they afford 

 is not pure. Sir Humphry Davy, in his Elements of Chemical 

 Philosophy, page 413, mentions a method very little ditferent 

 from those of other writers : but the gold alloyed with copper 

 thus obtained is always brittle ; whereas the German or Dutch 

 copper does not imj)air the ductility of gold in any degree what- 

 ever. It would be doing a material service to a certain class of 

 manufacturers, to have instructions from some of your correspon- 

 dents to manufacture this article. 

 I am, sir. 



Your most obedient humble servant, 

 Binniiigl;:im. DaVID LloYD. 



L. On Fulm'wating Silver. 

 To Mr. Tilloch. 



iSiR, — Ix vour last number, the follv and danger of allowing 

 mischievous boys the use of packets containing fulminating 

 nitrate nf silver are very properly exposed. All knowledge 

 however is useful, although its occasional misapplication may be 

 partially injurious. I'his is particularly applicable to. the use of 

 fulminating powder, wliich may be converted into an instrument 

 of household protection, in times like the present, when im- 

 mense munbers of individuals feel uiore inclined to rob than 

 work for a living. Its application to this purpose is equally 

 simple and safe. Let prepared packets of this fulminating pow- 

 der, such as were lately sold for idle and foolish purposes, be 

 placed round \.'indows and doors likely to be assailed by robbers, 

 every night, and removed every morning ; and should any attack 



be 



