»3» Analyjis of a new Variety of Lead Ore. 



becaufe the ox'ule of lead is foluble in this laft^ A precipitate fell down, and the remain- 

 ing liquor, filtered and neutralized, was fubmitted to the following tefls : 



Nitrate of lime aiForded no precipitate : the prefence, therefore, of the phofphoric, 

 arfenic, or molybdic acids» was entirely preduded. ^ 



Nitrate of barytcs afforded no precipitate, therefore no fulphuric acid was prefent. 



Nitrate of lead, a flight precipitate, but quickly foluble by the addition of water. 



Thefe appearances convinced me that none of thofe acids, hitherto found to mineralize 



lead ores were to be expe£ted in the fpecimen now to be examined ; and the properties of 



the precipitate caufcd by nitrate of lead, agreeing nearly with thofe of muriate of lead, 



I dropped in fome nitrate of filver : a very thick and abundant precipitate took place, which 



had all the chara£leriftics *, not to be miftaken, of muriate of filver. It weighed 42, 



which, according to Bergman, contain 7 of muriatic acid ; but according to Klaproth, in 



his analyfis of the molybdate of lead, 7 of muriatic acid faturate about 45 of oxide of lead ; 



and again, according to Bergman, 6 of carbonic acid faturate 34 of oxide of lead, which 



would have left a deficit of 8. The experiment was, therefore, repeated ; and being aware 



that ammonia could no more decompofe the whole of the muriate of lead, than could any 



other alkali, the nitrate of filver was dropped immediately into the nitric diflblution of the 



ore ; and upon repeating this eflay twice, 48 of muriate of filver were obtained each 



time, containing 8 of muriatic acid ; which in combination form 59 of muriate of lead ; 



the lead afterwards fubmitted to various proofs, wa« found to be perfe£l;ly pure, and the 



proportions may be eftabliflied as follows : 



Oxide of lead - - - ?i?n/r-. nj 



Muriatic acid - - - ^g J ^""'^^ ^^ ^^^'^ " " 59 



Oxide of lead ---q4?/-.i.fij 



Carbonic acid - - - ^^ J Carbonate of lead - ^ . 40 



99 99 



With about one of heavy fpar, as before mentioned. 



It does not, however, appear probable, that thefe two falts of lead exift feparately in the 

 ore ; its perfeft cryftallization and tranfparency fufficiently indicate it to be in the ftate of 

 a triple fait, or carbonated muriate of lead, combined on the above proportions, and 

 in the following order : 



Muriatic J> 8 



and \ acids Oxide of lead 85 



Carbonic j 6 



14 99 



The very great fcarcity of this ore preven'ted me from fubmittlng it to more experiments ; 

 however, upon expofing a certain quantity of it to a red heat, a thick vapour arofe, 



• I need mention no other than this ; muriate is the only fait of filver which is not foluble in almoft 

 every acid, and is inconteftibly the moft delicate and abfolute re-agent in cheraiftry; as well to dem»n. 

 ftrate the prefence, as to determine the quantity either of filver or muriatic acid. 



which 



