3]6 Mercury in Sea-Salt. 



fiibftance it is that I attribute the mercury I found in all the tin in the market, when I ope- 

 rated at that city. Being provided with marine acid from the fame works, at tke firft erec- 

 tion of the laboratory of Segovia, I again found this amalgam at the end of the folutions of 

 the tin of England, Mexico, and Monterey in Spain. 



I remained a long time perplexed with the explanation of thefe fa£ts, till chance, a fliort 

 time ago, difcovered to me the fource of this aftonifhing mercury. 



There is in the hiftory of copper a peculiar kind of oxidation, which appears to me to 

 have been hitherto unobferved. It takes place when plates of copper are kept in a bottle of 

 marine acid full and clofed. The copper, after having taken up about 17 per cent of 

 oxygen, whereas it can receive 25 in other acids, this copper is transformed into a white mu- 

 riate cryftallized in tetrahedrons ; which becomes violet-coloured by light, is infoluble in water, 

 foluble in ammoniac without colouring it, and has other curious properties, of which I Ihall 

 fpeak more fully hereafter. Being defirous of repeating this experiment with the marine acid 

 of Paris, I found, two days afterwards, that my plates of copper were rendered white. I 

 took them out, and examined them, and difcovered without difficulty that they were 

 changed by mercury. 



To dete£i: the exiftence of mercury in marine acid in a more direft way, I mixed it with 

 hepatic water. It became immediately turbid, and afterwards depofited a black ethiops. 

 This alfo is the habitude of the folutions of fublimate mercury with hepatic water. 

 ■ If marine acid of the fabric of Cadahaflb in La Mancha be mixed with the muriatic fo- 

 lution of tin which has been kept upon tin, the mixture foon becomes turbid, of a light 

 grey colour, and will depofit mercury on a piece of gold placed at the bottom of the veflel. 

 i have found as much as two grains in the pound of this acid. 



However little may be the utility of quoting the ancient chemifts, at this day, I fliall ne- 

 verthelefs offer fome pafTages which appear to (hew that it was known that mercury is con- 

 tained in marine fait. 



Boyle found a fmall quantity of mercury contained in a mixture of lead and marine acid, 

 left for a time in his laboratory. " This was fo much the lefs furprifing to me," fays he, "as 

 the principal ingredient was marine acid." On the Produftion of Principles., De Product. 

 Princip. p. 55. 



Does not this pafTage prove that the exiftence of mercury in common fait was not a new 

 fa£t to Boyle ? 



Athanafuis Kircher affirms, p. 316 of one of his treatlfes, of which I forgot the title when 

 I wrote this note, that mercury is obtained from fea-falt. In his time, the, fyftem of mer- 

 curification, and the mercuries of metals, were much in vogue. 



Beccher, Phyf. fubt. p. 205, obtained mercury from a mixture of fea-falt and clay. He 

 affirms, page 456, that he was aiTured that mercury might be augmented by means of fea- 

 falt, and afks, on this occafion, how much fea-falt may be contained in a pound of mercury ? 

 The reverfe of the queftion would have been better founded. 



Senac, in his Chemiftry, fpeaks alfo of mercury found in fea-faltl And, laftly, we fiad other 



traces 



