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afford fuch a ftriking contrad, when compared with 

 genuine cyder, or white-wine? 



When the metallick principle was precipitated by 

 an alcali, the wine m longer gave the brown coppery 

 tinge to the fteel pin, and that for an obvious reafon. 

 Copper unites with an alcali rather than with iron. 



On the whole, if we may rely on the above expe- 

 riments, does not the general refult afford a ftrong 

 prefumption, if not a proof, that the cyder-wine 

 contains a minute impregnation of copper ? Not fo 

 conftderabUy nor yet fo very palpable y (it is to be 

 hoped) as my ingenious correfpondent feems to 

 imagine, but yet fufficient to put the publick on 

 their guard concerning a liquor that comes in fo 

 very ^ quejlionable a Jhape.* 



It is a curious chemical fa6^, if it be really true, 

 that acid liquors? while kept boiling in copper vef- 

 fels, acquire little or m impregnation from the metal, 

 but prcfently begin to a6l upon it when left to 

 ftand in the cold. Can this be owing to the agita- 

 tion occafioned by boiling, or the cxpulfion of the 

 aerial acid ? Atmofphcrick air powerfully corrodes 

 copper, probably through the intervention of the 

 aerial, or rather nitrous acid, for both are now ac- 

 knowledged to be prefcnt in the atmofphere. But 

 Z 2 the 



