294 JOSEPH STRUTHERS 



the amalgamation process, by being held in suspension in the 

 water, and washed away with the sands and the tailings. 



In the chemical industries large quantities of mercury 

 are used as electrodes in several electrolytic processes, notably 

 in the electrolysis of brine to form sodium salts. The solution 

 of salt having been decomposed by the electric current, the 

 metallic sodium thereby set free at the cathode immediately 

 combines with the mercury, from which the sodium is sub- 

 sequently extracted by a treatment with water, forming so- 

 dium hydroxide (caustic soda). On account of its high 

 specific gravity, and its freedom from attack by many gases, 

 mercury is an invaluable material for the construction of 

 hquid seals in gas collecting apparatus, for making ther- 

 mometers and barometers, and for making electrical contacts 

 in certain apparatus used in physical laboratories and in- 

 dustrial processes. 



The quicksilver deposits of commercial importance in 

 California are situated in the coast range and are limited 

 to an area bounded by Trinity county on the north and 

 San Luis Obispo county on the south, both counties being 

 included. During 1902 San Benito county contributed 

 7,289 flasks, valued at $306,096, the product being derived 

 largely from the New Idria mine. In Napa county the chief 

 producer is the Napa consolidated mine at Oat Hill. In 

 the Knoxville district the Boston mine, formerly the Read- 

 ington mine, under the control of the Boston Quicksilver 

 Mining company and the Manhattan mine contributed to 

 the output. The total production for Napa county during 

 the year amounted to 7,300 flasks. Santa Clara county 

 was next in the order of quantity produced, contributing 

 5,779 flasks. The chief producer in this county was the 

 New Almaden mine, followed by the Guadalupe mine. The 

 New Almaden mine is the oldest quicksilver mine in the 

 United States. It was discovered and worked in 1824, when 

 California was under Mexican rule, and w^as then known as 

 the Chaboya mine. Later it was abandoned until 1845, 

 and since 1850 it has been worked continuously. 



As to the future of the quicksilver mining industr}^ of Cal- 

 ifornia the larger and better known mines have in a measure 



