4 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



tinguisliing" quicksilver with clay) and adding this material, which is 

 substantially blue mass, to the soil in which the vines are planted. The 

 process seemed at first successful, but subsecpiently failed to give the de- 

 sired result. Prof K. W. Hilgard' lias e.xperimented on the process and 

 found it entirely successful when properly carried out. No lead or oil should 

 be added to the quicksilver, and the soil either must be sandy or, after im- 

 pregnation witli mercury, must be warmed in a hot sun or by artificial 

 means, to saturate it with mercurial vapor. Should this process be widely 

 introduced it would greatly enlarge the market fur quicksilver and would 

 correspondingly benefit the mining industry. 



Comparison between various mining regions. QuicksilvCr luiS bcCU produCcd iu large 



quantities in but few localities. The principal productive regions have been 

 Almaden in Spain, Idi-ia in Austria, Kwei-Chau in Chinn, Huancavelica in 

 Peru, and California. Italy has yielded a little quicksilver for a long time 

 and a considerable number of localities elsewhere have had a temporary or 

 local importance, but none is to be compared with those enumerated in the 

 last sentence. Peru is now producing no quicksilver and the Chinese pro- 

 duction is small, but it is certain that the Chinese deposits are not exhausted 

 and Huancavelica may possibly resume production when the conditions for 

 intelligent exploitation are better. 



Such geological interest as attaches to the occurrence of exceptionally 

 large quantities of cinnabar is independent of the question of future produc- 

 tiveness, and a few historical notes on the past yield may he welcome to the 

 reader. 



The great quicksilver mine of the world is Almaden, which has been 

 worked since at least 415 years before the Christian era, and perhaps still 

 lono-er. What quantity of ore was extracted from it in ancient times and 

 in the Middle Ages there is no means of knowing, further than that Pliny 

 reports 10,000 pounds of cinnabar a year as brought to Rome from Almaden 

 (Sisapo). The product was certainly never large until the amalgamation 

 process was invented in 1557. Since that time the product has iticreased 

 pretty steadih-, and the output since 1850 is nearly equal to that of the 

 entire eighteenth centui-}'. The deposit is said to grow richer in depth 



' Science, vol. 6, 1885, p. 497, and vol. 7, 1886, p. 462. 



