818 BecquereVs improvement in Assay. 



metallic state , or in the nature of a sulphate, as usually occurs in Mexico and Peru, but 

 it becomes more complicated when the silver is mixed with other substances ; the use of 

 a small quantity of combustible matter is then indispensible in order to effect the roasting 

 at a low temperature. Ores are generally found in great quantities in those countries, but are 

 for the most part abandoned, owing to the want of sufficient fuel for effecting their amalgama- 

 tion, or to their being found at too great a distance from the sea to transport them to Europe, 

 unless at an enormous expense. In Columbia, where large masses of gold and silver 

 are found mixed with zinc, the richest are sometimes exported to Europe to be fused, whilst 

 the poorest and those of a medium quality are either rejected altogether, or used to so little 

 advantage that the mining companies lose by them. Exertions are now in progress for 

 introducing the new methods, which are equally applicable to amalgamation and to the 

 electro-chemical process. The silver ores which are most difficult of amalgamation, are 

 those which contain a large portion of copper and arsenic. Ores of this description are 

 found in considerable quantity, especially in Chili, where the inhabitants frequently offer 

 them to Europeans, by whom they are sometimes taken for ballast for want of freight, and 

 without any certainty of turning them to advantage. The great difficulty was to be able 

 to treat these substances in Europe so as to obtain, in separate portions, and at little expense, 

 all the silver, copper, and arsenic they contained. This problem has just been solved in 

 a satisfactory manner, and so as to secure immense advantages to new speculators, who 

 will no longer have to contend with the obstacles met with by their predecessors. On en- 

 quiring into the causes of the delay experienced in working the mines in America, it will be 

 seen that the principal ones arise from the high price of quicksilver, and the great difficulty of 

 draining the water by which the mines are inundated. This is not the case in Asia, in 

 the Russian possessions, which are rich in mineral productions, and yield larger profits 

 from day to day in consequence of the introduction of the improvements lately adopted 

 in Europe for reducing metallic ores. In the silver mines of Altaic the expenses for extracting 

 the ore, process of reduction, and of the establishment, do not amount to a quarter of the 

 rough produce, although the ore in general is of slight tenacity. These advantages are 

 owing to the moderate price of labour, the abundant supply of combustible matter and 

 substances required in the fusing, and which are not to be had in America, especially 

 in Mexico, and the Cordilleras. The electro-chemical process can be easily applied to 

 the ores at Altaic ; however in countries where sufficient fuel is at hand, and salt cannot be pro- 

 cured, the fusing operation will be always preferred, except in cases of complex ores, which 

 often exercise the ingenuity of metallurgists. There are but few silver mines worked in Russia. 

 The only ones of importance are those of Altaie, Nertchinsk, and those of the Caucasus 

 and the Ural ; but the great source of mineral riches in that kingdom consists principally 

 of the gold and platina dust, sands,) the washing of which engrosses the chief attention 

 of the government. This process, though methodically conducted, is very imperfect, for 

 a large quantity of the gold contained in the sand is lost ; the proceeds, however, are consider- 

 able; during the last year no less than 12,2001bs. were obtained, upwards of SOO.OCOZ. value. 

 The argentiferous and auriferous galenae which have been subjected to the electro-chemical 

 process are perfectly fit for the extraction of gold and silver by washing. This method 

 requires that the ores should be pulverised and roasted so as to separate the metal from 

 the pyrithes and other compounds which detain it. The silver and lead being removed, 

 the ore, thus reduced to about half of its weight, can be washed with the greatest facility, 

 and one man can wash several hundred pounds per day. This method was tried with the 

 galena (very argentiferous) discovered a few years since at St. Santin Cantales, in the depart- 

 ment of Cantal, and which yield not more than 2| grains of gold in every 20Olbs. of ore, 

 with 30 per cent, of lead. But upon adopting the electro-chemical process, the same quantity 

 of ore produced something more than three drachms of gold. From this important result 

 it is supposed that the rocks in that part of the country are auriferous, as might also be 

 inferred from the name of the place, Aurilac, (auri lacus.J Another great advantage of 



