IIG Agricultural ?.iuseum 



aqua regia, that is, blue vitriol, which is sometimes I'ouiid 

 solid, but more frequently iu mineral waters ; from this 

 the copper may be precipitpicdby iron immediately. 



We have laiely had many opinions published, of me- 

 tals i eiiig found in mineial waters, combined with vari- 

 ous substances. I never examined any mineral water 

 in wli'ch I found the metals combined with any sub- 

 sta;.ce but vitriolic acid ; and am certain many authors 

 liave been misled, by not knowing this property of metal- 

 lic salts, viz. that if we dissolve them in a small proporti- 

 on of water, or if there be superfluous acid, the solution 

 will remain perfect when exposed to the air; but, if the 

 acid be perfectly saturated with the metal, and the pro. 

 poi'tion of water to the meta lie salt be very great, on 

 exposure to the air it is decomposed, the metal precipi- 

 tating in Iht form of a calx, and the acid being lost. 

 This may easily be tried, by taking common green or 

 blue vitrol, dissolving an ounce in three ounces of water, 

 by boiling, letting them stand to cool, and filtering the 

 solution. If this solution be exposed to the air it will re-' 

 main perfect ; but, if v/e drop a drop or two of it into a 

 wine-glass full of water, in a few minute? the transparen- 

 cy of the Abater will begin to be disturbed, and the me- 

 tal in a short time will fall down, in a red powder if it be 

 iron, in a blue powder if it be copper. 



Anhundred grains of the ore is sufficient to give the 

 copper contained, to oj)p hundredth part; if greater ac- 

 curacy be required, 1000 grains may be used,' 



The mixture of nitrous and muriatic acid is the most 

 proper acid mcnsiruum for copper ores ; muriatic acid 

 dissolving mosi readily the calces of metals, and nitrons 

 p.cid when they are in their metallic form ; a metal in its 

 met.iUiC form being a compound of a pure calx and a 

 substance which has been called inflammable air, but 

 which is an oil, found out by Stahl to exist in metals, and 

 which we would call the oil of metals. The nitrous acid 

 decomposes this oil, at the same time that it acts on the 

 calx itself, and leaves it uiso to be acted upon by the 

 muriatic acid. 



