548 PHILOSOPHICAL TRANSACTIONS. [aNNO 1789. 



I extracted 12 per cent, of refuse from some gold-dust, and on examination found 

 it to be sand and filings of iron, which last was not likely to have been with it 

 in its native state, but probably employed for the purpose of adulteration. Two 

 days journey from Tissoolumboo there is a lead mine. The ore is much the 

 same as that found in Derbyshire, mineralized by sulphur, and the metal ob- 

 tained by the very simple operation of fusion alone. Most lead contains a por- 

 tion of silver, and some in the proportion to make it an object to work the lead 

 ore for the sake of the silver. Cinnabar, containing a large proportion of quick- 

 silver, is found in Thibet, and might be advantageously employed for the purpose 

 of extracting this metal. The process is simple, by distillation; but to carry it 

 on in the great would require more fuel than the country can well supply. I 

 have seen ores and loose stones containing copper, and have not a doubt of its 

 being to be found in great abundance in the country. Iron is more frequently 

 to be met with in Boutan than Thibet; and, were it more common, the difficulty 

 of procuring proper fuel for smelting the less valuable ores, must prove an insu- 

 perable objection to the working them. The dung of animals is the only substi- 

 tute they have for fire-wood, and with that alone they will never be able to excite 

 a degree of heat sufficiently intense for such purposes. Thus situated, the most 

 valuable discovery for them would be ,that of a coal mine. In some parts of 

 China bordering on Thibet, coal is found and used as fuel. 



Tincal, the nature and production of which we have only hitherto been able 

 to guess at, is now well known, and Thibet, from whence we are supplied, con- 

 tains it in inexhaustible quantities. It is a fossil brought to market in the state 

 it is dug out of the lake, and afterwards refined into borax by ourselves. Rock 

 salt is likewise found in great abundance in Thibet. The lake, from whence 

 tincal and rock salt are collected, is about 15 days journey from Tissoolumboo, 

 and to the northward of it. It is encompassed on all sides by rocky hills, with- 

 out any brooks or rivulets near at hand; but its waters are supplied by springs, 

 which being saltish to the taste are not used by the natives. The tincal is depo- 

 sited or formed in the bed of the lake ; and those who go to collect it, dig it up 

 in large masses, which they afterwards break into small pieces for the conve- 

 nience of carriage, exposing it to the air to dry. Though tincal has been col- 

 lected from this lake for a great length of time, the quantity is not perceptibly 

 diminished; and as the cavities made by digging it soon wear out or fill up, it is 

 an opinion with the people, that the formation of fresh tincal is going on. They 

 have never yet met with It in dry ground or high situations, but it is found in 

 the shallowest depths, and the borders of the lake, which deepening gradually 

 from the edges towards the centre contains too much water to admit of their 

 searching for the tincal conveniently; but from the deepest parts they bring up 

 rock salt, which is not to be found in the shallows, or near the bank. The 



