574 J A M A I C A. 



folution of faccharum fi^tnrtii in water ; or folutlon of lead in the 

 nitrous acid ; by its I'udden tarnifhing of filver ; and by the fetid 

 fmell refcmbliiig a rotten egg, or fcowerings of a foul gunbarrel, on 

 dropping in folution of alcalis. 



6. Copper. 

 This is difcovered by fpirit of fal ammoniac, made with quick- 

 lime ; which, if the fmallell: particles of copper are prefent in the 

 water, caufe it to ailiime a very beautiful blue colour. Iron preci- 

 pitates this metal. A plate of iron laid in water, impregnated with 

 copper, will foon be covered with an incrufration of it. 



•J. Lead 

 is not a native impregnation of mineral waters; it is generally 

 found in the earth united with fulphur in form of an ore. Waters, 

 impregnated with its rufl or mineral vapour, ftrike a pink or red 

 colour with aqiiaforlis, and are highly poifonouG ; for which reafon, 

 on liquor fhould ever be kept in leaded cifterns or other veflels, either 

 for drink or preparing food. That lead, when diflblved by fire, or 

 corroded by an acid, emits poifonous effluvia, is fufficiently fhewn 

 by the difeafes incident to plumbers and painters. But much lefs 

 heat than is required for melting lead, is capable of detaching fuch 

 pernicious effluvia. The heat in the bowels of the earth in this 

 climate may be juftly liifpetled, efpecially in Liquanea, and other 

 parts where lead ore has been found to work this efted ; fo far at 

 lead as to impregnate any fprings of water, which circulate among 

 this ore. Water alone, if not perfeclly pure, is a fufficient agent to 

 caufe a folution of the metallic poifon ; and has been found by ex- 

 perience to imbibe it largely. The noted colic of Amfterdam, 

 which for a long time eluded the fearch of phyficians with refpetSt 

 to its caufe, took its rife from this poifonous impregnation of tlie 

 rain water, which was colledled in leaden refervoirs, after firll 

 lodging on fiat leaded houfe roofs, upon which the leaves of trees 

 had fallen in great abundance about autumn. Thefe excited a fer- 

 mentation, which corroded the lead, and contaminated the water. 

 Tronchin relates that whole families were feized with this dreadful 

 colic: eleven perfons fell ill with it at once in one houfe; who, 

 upon new covering the roof with other materials, and changing their 

 water, recovered. Dr. Baker fufpeAfVs, that the lead ufed about the 



works 



