Observations on the Vurity of Standard Gold, 1 4 1 



Many persons will probably doubt that gold is found in 

 nature so near a state of perfect purity, although Strabo 

 intimates that perfectly pure gold was found in the Alps, 

 and Pliny is cited as asserting that no silver was ever found 

 in it. But without remaining in suspense with respect to 

 the assertions and opinions of others, I am enabled from 

 my own experiments to remove all uncertainty, having 

 ascertained that native gold is 24 carats (1000). 



I had for some time the charge of the fine collection of 

 natural historv belonging to our sovereign, who was fond of 

 that science. His majesty possessed many specimens ot 

 mineralized gold and native gold, among which I remarked 

 two well formed crystals of gold, viz. one cubical, the other 

 prismatic with four faces, surmounted by a pyramid with 

 four faces also. It would be interesting to know what 

 substances united to the gold have determined these various 

 figures formed naturally in the bowels of the earth, and 

 which are totally different from those which are produced 

 in the laboratories of the chemist after melted gold is 

 cooled. The cube is very pale, the prism is higher co- 

 loured; but these two crystals, which I found by chance, 

 (when choosing among several natural grains,) are unique 

 in this depot ; so that it would be improper to subject 

 them to an examination which would alter their form. 

 An unshapen specimen, but at the same time a remark- 

 able one, from the Brazils, enriches this collection. The 

 weight of this piece is about fourteen pounds ; and I ex- 

 amined a bit of it by the cupel and by quartatidn, without 

 omitting also to examine its solution in the nitro-muriatic 

 acid, with the sulphate of iron, and with neutral salts with 

 a base of potash. I have been convinced by all these ope- 

 rations, that this was pure gold of 24 carats without any 

 alloy of inferior metal. 



From all that I can learn, therefore, it appears that gold 

 is found in a native state in various degrees of purity, and 

 to prove this baa been the object of the present dissertation. 



tive gold. M.Deluc informs us that the gold found at W'icklow in Ireland 

 was alloyed with a ninth part of its weight in silver. 



M. Fabbroni is the iirst who has demonstrated that native gold is found 

 in a state of purity: thu is a most important observation; but it does not 

 teem to destroy the idea that native gold is a natural alloy of gold and silver: 

 a principle establislud by a great number of facts, and to which we as yet 

 know but one exception. 



It would be interesting to ascertain whether lead is present in ancient coins 

 or medals : this would be the surest method of determining whether th^ 

 ancients refined their gold, or employed it as nature presented it. 



XXIII. An 



