Sub-marine Vejfd. — Purification of Copper. 235 



above the EngUfli (hipping at Philadelphia, in December, 1777. I was unacquainted with 

 the river, and obliged to depend upon a gentleman very iraperfeftly acquainted with that 

 part of it, as I afterwards found. We went as near the (hipping as he durft venture ; I 

 believe the darknefs of the night greatly deceived him, as it did me. We fet them adrift, 

 to fall with the ebb, upon the (hipping. Had we been within (ixty rods, I believe they 

 mud have fallen in with them immediately, as I defigned ; but as I afterwards found, they 

 were fet adrift much too far diftant, and did not arrive, until after being detained fome 

 time by froft, they advanced in the day time, in a difperfed (ituation, and under great 

 difadvantages. One of them blew up a boat, with feveral perfons in it, who imprudently 

 handled it too freely, and thus gave the Britifli that alarm, which brought on the battle of 

 the kegs. 



The above velTel, magazine, &c. were projected in the year 1771, but not completed, 

 until the year I775. 



D. BUSHNELL. 



X. 



Quejlion refpeSing the Purijication of Copper for alloying Gold. By X. Y. 



To Mr. NICHOLSON, 



SIR,' 



Nenvcqflle-upon-Tyne, Feb. 18, 1800, 



I 



BEG leave, through the medium of your valuable publication, to requeft the favour of 

 any of your correfpondents to inform me of the beft method of obtaining copper in its 

 utmoft (late of purity, and (it for alloying gold without occa(ioning that brittlenefs which 

 always arifes from ufing copper, even of the (ineft kind ufually obtained in commerce. 

 The duftility of the gold may be reftored by fubfequent fufions, but this occafions con- 

 fiderable lofs and difappointment to the workman, which do not happen when the copper 

 is perfeftly re(ined. I have looked into feveral chemical works, but without obtaining 

 the fatisfadlion I want -, nor would I be fo folicitous about this information, could I, at 

 any time, procure copper fit for this purpofe. 



I am, SIR, 



Your's, &c. 



X. Y. 



Hh2 On 



