VALUE AND USES. 3 



has been at a s!i<^-lit preniiuni. The rnhit value is thus sufficiently close to 

 the average for the present purpose. The data as to the gold and silver 

 products are compiled from figures given by Dr Soetbeer and Dr. Kimball.^ 

 The figures for tin are only approximations, but are close enough for the 

 purpose." In estimating the total quicksilver 1 have supposed, with Mr. 

 Randol, that the average yearly product, besides that of Almaden, Idria, 

 and California, is 2,000 flasks.' The mean value is assumed at S.50 a flask. 



Tlic world's product of four metals from January, 1S50, to January, ISSO. 



Uses for quicksilver. — Tlic low valuc of quicksil vci', which is abnormally small 

 considering the comparative rarity of the metal, is due to its restricted use. 

 It is true that the number of purposes to which qiiifksilver is applied is 

 very great: but most of these applications imply the consumption of trifling 

 quantities of the metal. A single flask of quicksilver in the form of niir- 

 ror-backs, thermometers, or medicines goes a long way. The great mass 

 of the metal is employed in tlie amalgamation of ores and in the manufact- 

 ure of vermilion. k?> only certain silver ores can be economically amalga- 

 mated, tlie demand for this purpose fluctuates greatly. The bullion of the 

 Comstock was all extracted by this process, but amalgamation is not appli- 

 cable to any of the ores of Leadville. The demand for vermilion also is 

 limited by tlie competition of other red pigments. A few years since, Mr. 

 J. A. Baur, of San Francisco, devised a means for the extirpation of phyl- 

 loxera, which consists in intimately mixing clay with (juicksilver (or "ex- 



' Report of the Diroctof of the Miut, 1«38, pp. 169 and 171. 



- They arc estimated from data coutaiued iu Mr. J. A. Phillip.s's Ore Depusit.'s and .statistics which 

 I gathered at the Paris Exposition of 187.-J (Reports of tlie United States Commissioners, vol. 4). 



' This for the later years is much too small. The Tu.scau mines are said to be iiroducing about six 

 hundred tlasks a month. 



