') 
. 
4799-1. 
nothing farther than that it contains about 
100,000* inhabitants, including the flaves; 
thatthe churches are very rich in filver 
utenfils; and ‘that its whole militia con- 
fifts of only soo men, of a moft melancholy 
appearance, without uniforms, and with- 
out cannon ; and of whom one-half parade 
with wooden muikets. Nor of the city of 
Chuquifaca,.or La Plata, which lies. at a 
fhort diftance from Potofi, do we learn any 
‘thing farther in Helms’s Journal than that 
it is the feat of an arch-bifhop, of the ec- 
clefiaftical tribunal for the whole kingdom 
of La Plata, and of an univerfity. 
The rich filver-ore mountain Potofi, at ’ 
whofe foot the city is built, refembles a 
fugar-loaf, is almoft fix miles in circum- 
ference, chiefly !compofed of a. yellow 
very firm argillaceous flate, and is full of 
veins of ferruginous quartz, in which filver- 
horn-ore and more rarely brittle vitreous 
ore are found interfperfed. ‘Thefe rude 
ores are there called paco ores, and contain, 
on an ayerage, 6 to 8 ounces of filver in 
every caxon, .or fiity hundred weight. 
They fometimes likewife meet with folid 
filver-ore efpecially with greyifh-brown- 
ore, each caxon of which yields 20 marks 
of filver. Above 300 mines or pits are 
worked, buf all of them irregularly, and, 
as if it were merely for plunder; few ofs 
them therefore penetrate to a greater depth 
than about 70 yards. Here they were to- 
tally unacquainted with machinery. for 
pumping out the water from the pits, or 
for extracting and preparing the ore, ex- 
cept a wretched pounding machine, which 
was put in motion by means of a plain 
horizontal -water-wheel.; and in pafling it 
through the fieves, at leaft 20 per ‘ceitt. of 
ore was-loft. A main conduit. which had 
been begun in'1779, and in the courfe of 
nine years had, at an incredible expence; 
been carried on: as far as 1425 Saxon élls, 
was even at its mouth muck too high, and 
yet had been made to flope one ell to 
every 32 ells, fo that it would not have 
come deep enough into hardly any of the 
pits to free it from water. The unwieldy 
hammer of twenty pound weight exhaufted 
the ftrength of the miner, the iron a foot 
long was a great deal too incommodious, 
and the thick tallow-candles wound round 
with wool contaminated the air. Still 
greater, if poffible, was the ignorance of . 
_the workmen at the fmelting-houfes at 
f. 
a 
¥ 
Potofi, who by their method of amaiga- 
mation were hardly able to gain two-thirds 
of the filver contained in the paco-ore, loft 
* The Governor was himielf ignorant of 
the exaé&t number of inhabitants or hearths; 
Montuty Mac, No, Lie 


Defcription of the Mines of Potoft. 
7989 
above a third in the procefs, and for every 
tmark of purefilver they gained, deftroyed 
one, frequently two, marks of quickfilver. 
Only to compare the excellent method of 
amalgamation invented by Baron Born, 
with the barbarous procefs ufed by thele 
Indians, would be an envious degradation 
of the former. —In the Royal Mint at Po- 
toli, -affair$° were not better conducted. 
Nvery hundred weight of refined copper 
ufed for’alloy.in the gold and filver coin, 
coft the king 200 piaftres, through the 
grofs ignorance. of ‘the overfeers of the 
work, who fpent a whole month in roaft- 
ing and calcining it; but Helms, in. 5% 
hours, and at lefs than one twentieth part 
of the expence, brought it toa greater de- 
sree of finenefs.— Thefe evils the German 
commiffioners endeavoured as much as 
potfible to remove.—A miner of the name 
of Weber, dus two deep conduits (for 
freeing the mines from water) in the : 
mountain of ‘Potofi; Baron von Norden- 
fiycht ereéted ‘proper machinery ; and 
Helms built amalgamation-works, and 
gave leffons in metallurgy. As foon, 
then, as the water in the pits can be got 
under, the; mines of Potofi will be inva 
more flouriffing condition, than ever, 
‘and that by the fkill and, indufiry of 
German mineralogifts. | However, the 
total want of timber on this naked ridge 
of mountains very.much retards the work. 
From Tucuman .to. within fix miles. of 
Potofi we find here and there in the valleys 
{mall trees and bufhes ; but farther. to-_ 
wards Potofi the fides of the mountains are 
covered with only a thin mofs. Brufh- 
wood and charcoal for fuel. muft there= 
fore be brought from a diftance of from 
ten to twenty miles, and larger trees fit for 
building even from Tucuman, and dragged 
acrofs the mountains by the hands of men. 
A: beam 20 Hungarian inches in diameter, 
and 8 ells in length,’ cofts at\ Potofi 2000 
piaftres.—According to a lift communi-~ 
cated by Helms, 30 gold mines (molly 
works where they wath gold from, the 
fand) 27 filver-mines, 7 copper-mines, 
2 tin, and 7 lead-mines, are wrought in 
the whole kingdom of La Plata. The re- 
venue to the king from thefe mines is ‘aid 
to amount annually to 42 millions of pi- 
aftres (?): and if they poffeffed more 
knowledge and economy, it might very 
eafily be doubled. Indecd, if all the veins 
of ore, &c. were fought for and wrought 
with but moderate fkilland diligence, this 
kingdom alone might yield every year 
twenty, and even thirty, millions. 
[Zo be concluded. im our next.) 
i - Ta 
5 
ee 
nearer 


