SILVER, 



ire found confiderable maffes of native filver. Although 

 the new continent has not hitherto produced fiiigle mafles 

 of native filver equal to what have been found in the old, 

 the metal is more abundant in a Hate of perfeft purity in 

 - Mexico and P?ru than in any other quarter of the globe, 

 not in malies, but in particles difleminated through the 

 enormous quantity of the ore called pacos. The refult of 

 a general invettigation of the richnefs of different mines is, 

 that the mean richnefs of the different ores is not more than 

 from three to four ounces of filver in every fixteen hundred 

 pounds of ore. According to this refult, the ore contains, 

 on the average, two ounces and two-fifths per quintal. 

 It had formerly been aflcrted, that no ores were worked in 

 Mexico that did not contain one-third part of filver. The 

 filver-ores of Peru are not richer on the average than thofe 

 of Mexico. The diftrift of Guanaxlo has before been 

 mentioned as furnifhing more than one-fourth of the filver 

 annually extradled in America, the riches of the mines here 

 being fuperior to the celebrated repofitory at Potofi : they 

 are all worked in one extcnfive vein. Among thefe mines, 

 that of the count Valenciana is one of the richelt : the 

 average produce of filver is four ounces of filver from a 

 quintal of ore. 



The whole weight of filver from the vein of Guanaxto, 

 on an annual average from 1786 to the year 1803, has 

 been 556,000 marcs, or 364,911 lbs. troy; and in thirty- 

 eight years the weight of gold and filver, from the fame 

 vein, has been 12,700,000 pounds troy. In average years 

 it yields from 500,000 to 600,000 marcs of filver, and 

 from 1500 to 1600 marcs of gold. It has been doubted by 

 fomeperfons whether this be really a vein, or a metallic bed, as 

 in fome parts of its cnurfe it is parallel between the beds, or 

 ftrata of the rock. It pafies through both flate and por- 

 phyry, and is metalliferous in both. Thou^-h it has been 

 before ftated that the extent of this vein is more than 

 42,000 feet ; yet the enormous mafs of filver which it 

 has fupplied for the lail hundred years, fufficient alone to 

 change the price of commodities in Europe, has been ex- 

 trafted from an extent of lefs than 2000 feet ; for where 

 this vein is not widened by branches, its general width 

 may be Hated at from 38 to 48 feet. It is for the mofl 

 part feparated into three malfes, divided by banks of mine- 

 ral matter, or by part of the matrix deltitutc of ore. 



At Valenciana the vein cQntinues undivided to the depth 

 of 557 feet, and then divides into three branches ; and its 

 width, from the floor to the roof, is from 164 to 196 feet. 

 Of thefe three branches of the vein, there is in general only 

 one which is rich in metals. Sometimes, when thefe three 

 branches unite, the mine is uncommonly rich. In this cele- 

 brated vein there is a certain middle region, which may be 

 confidfred as a repofitory of greater riches, for above and 

 below this region the ores are poor in filver. 



At Valenciana the rich minerals have been in the grcateft 

 abundance, 300 and 1 100 feet below the mouth of the 

 gallery. 



The labour of the miner is entirely free throughout the 

 whole kingdom of Spain, and no Indian or Meltizoe can be 

 fined to work in the mines. The Mexican miner gains 

 from i/. to i/. 4^. fterling per week of fix days. The men 

 employed in agriculture do not gain more than a third of 

 that fum. The miners work nearly naked, and are fearched 

 in the mod indelicate manner on leaving the mine. They 

 frequently conceal fragments of native filver and filver-ores 

 in their hair, under their arm-pits, in their mouths, and even 

 m the anus, into which they force cylinders of clay contain- 

 ing the metal. Thefe cylinders are called longanas. A 

 regifter is kept of the filver found in different parts of tiie 



body. In the mine of Valenciana, the value of thefe itolen 

 minerals, a great part inclofed in the longanas, amounted, 

 from the year 1774 to 1787, to 30,000/. iferhng. 



The filver is extrafted from its ores in New Spain by 

 amalgamation with mercury, and by fmelting : the propor- 

 tion of filver extrafted by mercury is 3^ to i of that extrafted 

 by fmelting ; and as fuel is becoming fcarce, the quantity 

 of filver extracted by amalgamation increafts, the fmelting 

 being very imperfeftly condufted. 



The Mexican miners do not appear to follow any fixed 

 principle in the feleftion of minerals dellined to fmelting or 

 amalgamation ; for in one diftricl they fmelt the fame ores, 

 which in another they believe can only be managed with 

 mercury ; and it is frequently the abundance or fcarcity of 

 mercury which determines the miner in the choice of his 

 method. In general they fmelt the argentiferous galena, 

 and the mixed minerals of blende and vitreous copper. 

 The pacos, the vitreous, red, and corneous filver-ores, the 

 grey copper-ore rich in filver, and the meagre ores, dilfemi- 

 nated in fmall quantities in the matrix, they find it more 

 profitable to amalgamate. 



All the metallic wealth of the Spanifh colonies is in the 

 hands of individuals. The government pofleiTes no other 

 mine than that of Huanca Velica in Peru, which has been 

 long abandoned. The individual receives from the king a 

 grant of a certain number of meafures, on the direftion of a 

 vein or bed ; and they are only held to pay very moderate 

 duties on the minerals cxtracfed. Thefe duties have been 

 valued on the average throughout all Spanifii America at 

 1 1^ per cent, of the filver, and three per cent, for the gold. 

 In the fpace of a hundred years, the annual produce of the 

 Mexican mines has increafed from twenty-five to one hun- 

 dred and ten millions of francs. The produce of the mines 

 in Peru has of late years been rather decreafing, which Hum- 

 boldt attributes to its being worfe governed than Mexico. 

 The procefs of extradlion feems alfo to be condufted upon 

 worle principles than in New Spain, though in neither of 

 thefe diltrifks is fmelting, or amalgamation, performed with 

 much (kill ; for, according to M. Humboldt,- the quantity 

 of mercury annually confumed in New Spain exceeds two 

 million one hundred thoufand pounds troy. The mercury 

 is feparated from the amalgam by diliillation ; but in the 

 whole procefs, the Mexicans wafte eight times more than 

 would be neceffary, were the procefs conducted in tlie fame 

 manner as at Freyberg. 



The following table will fhew the annual produce of gold 

 and filver in the mines of Europe, northern Alia, and Ame- 

 rica, as given by M. Humboldt, in kilogrammes. It may 

 be regarded rather as an approximation to the real amount, 

 than as a very accurate ilatement, the amount of Englifli 

 filver not being included ; perhaps this may be eflimated at 

 4000 lbs. troy. 



The kilogramme, it has been before ftated, is rather more 

 than 2 lb. 8 o/.. troy. It is impofiible to value the quantity 

 of gold and filver annually extrafted on the whole globe ; 

 for we are unacquainted with the amount of what is pro- 

 cured in the interior of Africa, and the central parts of Afia, 

 Tonquiu, Cliina, and .Japan. The quantity of gold and 

 filver formerly brought by the Dutch from the latter coun- 

 try proves tiiat it is rich in tlie precious metals. We may 

 draw the fame conclufion refpetting the northern frontiers 

 of China and other parts of Afia ; and the quantity 'f 



gold. 



