32 WRITINGS OF JAMES SMITHSON. 



ACCOUNT OF A DISCOVERY OF NATIVE 

 MINIUM. 



From the Philosophical Transactions of the Royal Society of London, 

 Vol. XCVI, Part I, 1806, p. 267. Read April 24, 1806. 



IN A LETTER TO THE RIGHT HON. SIR JOSEPH BANKS, 

 K. B. P. R. S. 



MY DEAR SIR : I beg leave to acquaint you with a dis- 

 covery which I have lately made, as it adds a new, and 

 perhaps it may be thought an interesting, species to the 

 ores of lead. I have found minium native in the earth. 



It is disseminated in small quantity, in the substance of a 

 compact carbonate of zinc. 



Its appearance in general is that of a matter in a pulveru- 

 lent state, but in places it shows to a lens a flaky and crys- 

 talline texture. 



Its colour is like that of factitious minium, a vivid red 

 with a cast of yellow. 



Gently heated at the blowpipe it assumes a darker colour, 

 but on cooling it returns to its original red. At a stronger 

 heat it melts to litharge. On the charcoal it reduces to 

 lead. 



In dilute white acid of nitre, it becomes of a coffee 

 colour. On the addition of a little sugar, this brown calx 

 dissolves, and produces a colourless solution. 



By putting it into marine acid with a little leaf gold, the 

 gold is soon intirely dissolved. 



When it is inclosed in a small bottle with marine acid, 

 and a little bit of paper tinged by turnsol is fixed to the 

 cork, the paper in a short time entirely loses its blue colour, 

 and becomes white. A strip of common blue paper, whose 

 colouring matter is indigo, placed in the same situation 

 undergoes the same change. 



