Or; tilt EfftB of a Mt.tttixe of Tin •uutlo GaUt^ »4k 



«fs tlie memoir in queftion. He appears to be convinced that tlie worlcj had adopted a» 

 erroneous opinion relpefting the objedl of the paper previous to its appearance } whence it 

 follows, that this Journal, which is defervedly efteemod, and of wide circulation, cannot 

 fail to produce a ftrong iinpreflion in this refpetl, which ought to be contradidted. It is 

 in fa£l founded on operations which have not been purfued with fuiEcient accuracy ; and 

 on this account they tend to produce a falfe fecurity in the mind of artifts who werk the 

 moft precious of metals. 



It has long been a received fa£J: among metallurgifts, obferves the editor, that tin mixed 

 ■with gold in the fmalleft quantity, either in fubftance or in vapour, is totally deflruftive- 

 of the malleability of that metal. But Mr. V/ouIfe, fellow of the Royal Society of Lon- 

 don, communicated to that Society, in 17^4, a memoir of Mr. Alchorne, afTayer at the 

 Mint in the Tower of London, and fince printed in the Philofophical Tranfa£\ions, iri 

 which he proves, that tin may be mixed with gold in a moder.ate quantity without pro- 

 ducing thefe bad effects. Thefe experiments, he adds, have not been contradicted ; not- 

 withftanding which, feveral of the molt celebrated authors have continued to follow the 

 ancient opinion, thriagh in no refpeft founded upon faft. It may therefore be fuppofed, 

 that the memoir of IMr. Alchorne has not been fufficiently known and attended to ; for 

 which reafon I have thought proper to give an abitra£t, to make it more generally known. 



M. iilchorne relates, that he had long doubted this extraordinary property attributed to 

 tin ; and that an opportunity having offered, he made various experiments on that fubjeft. 

 He mixed twelve ounces of fine gold with different j^roportions of tin from fixty grains to 

 half an ounce. Thefe compounds were beaten under the hammer, pafTcd through the 

 laminating rollers, and ftruck in the fiy-prefs without (hewing any brittlenefs. He like- 

 wife attempted to expofe gold to the vapour of tin ; for which purpofe he put twelve 

 ounces of gold of 22 carats into a fmall crucible, which he placed in a larger crucible, 

 and furrounded it with tin, and fubjected the whole to a confiderable heat for half an 

 hour ; but the gold loft nothing of its ductility. He carried his refearches flill farther : 

 he alloyed the foregoing mixtures with copper, and afterwards added tin to the gold thus 

 alloyed with different proportions of copper and fdver ; but in all the various cafes, twelve 

 ounces of gold alloyed with tin in the quantity of half an ounce, and of copper two ounces 

 and a half, fuffered hammering and laminating to the thicknefs of ftrong paper, and could 

 be wrought into fmall toys and drawn into fine wire with the fame facility as the gold of 

 commerce. 



M. Alchorne obfervcs, that the old opinion adopted by fo many authors owes its or!- • 

 gin probably to the arfenic which tin commonly contains, as he found that twelve grains 

 of that femi-metal in regulus rendered the fame number of ounces of gold brittle. Whence 

 he concludes that tin, like the other bafer metals, does not injure gold, but hi proportion 

 to the quantity of arfenic it contains, and that there is nothing in tin which can deprive 

 gold of its qualities, as was before obferved. 



From this fhort account of the experiments and obfervations of M. Akiiorne, we (cc 

 that he afHrms that gold, whether pure or alloyed, being fufed with tin in the proportion of 

 one part of the former to twenty-four of the latter, forms an alloy which preferves ducli- 

 lity fufficient to endure hammering and laminating to the thicknefs of ftrong paper, to be 

 ufedin toys and drawn into fin* wire with the fame facility as the common ftaadard gold. 



Thoiiglt 



