POSITION OF THE ORE — EXTRACTION OF METAL. 35 



quartz, while, as it widens, the sulphuret is found to take its place, and that, most fraquently, 

 suddenly, and not by gradual substitution ; external to the quartz vein is a layer of oxide iron 

 (limonite) into which the sulphuret sends cross filaments- the limonite bounds the quartz vein 

 on both sides, which latter presents the appearance of a succession of deposits out of a siliceous 

 solution into which the cinnabar was carried, and, by its superior density, supplanted the silica 

 in the even line of deposit. 



The trend of the small range in which the cinnabar vein is located is N. E. and S. W., and 

 the slate rock and serpentine have a westerly dip. Felspathic trap cuts through this, and is 

 accompanied- by quartz, and the mineral accompanies the quartz and the trap. The vein is 

 vertical, or nearly so, and is about eight feet wide at the level of the adit. Crystals of cinna- 

 bar were not observed while examining the ore in place, nor could it be ascertained that metallic 

 mercury was found associated with the sulphuret. 



The furnaces at the hacienda are 13 in number. The retorts are of brick, about 5 feet long 

 and 12 inches diameter in the clear; at the further extremities three flues connect with iron 

 stove-pipe chimneys, leading to a spacious cool chamber, and are cooled by water playing on 

 their outsides, so as to condense the volatilized mercury. 



The duration of the charge in the retort is six hours, and the fuel used is the wood from the 

 mountain. Under the strong heat the ore, sulphuret of mercury, is first volatilized and then 

 decomposed, the sulphur passing off and the mercury retained by the cooling of the flues which 

 lead to the receiving chamber. It is obvious to any one acquainted with metallurgic operations 

 that some of the mercury is lost by this process ; this, in fact, occurs to a large extent, pro- 

 ducing waste of ore and ill health among the furnace men, with whom salivation is no uncommon 

 occurrence, followed by tremblings and occasionally total paralysis, and in one noted instance 

 by insanity. On account of its unhealthiness, the men are allowed to work only two weeks 

 connectedly at the furnaces, during which time they receive double pay. On the other hand, 

 the miners are a healthy class, never being compelled to drop work from any effect of mercurial 

 poison, so that the sickness of the furnace men is due to the escape of mercury from waste in 

 conducting the processes. The present mode of sublimation by heat alone is adopted from sup- 

 posed motives of economy, but it is a matter of little doubt that more is lost than gained by 

 that method of saving. 



Under the former management of the works iron retorts were used, and lime used along with 

 the cinnabar to reduce it, by which an economy of fuel was obt3,ined, as the sulphur is separated, 

 from the mercury at a lower temperature in the presence of the lime ; but, since the hacienda has 

 come under the control of Mr, Halleck, of San Francisco, clay retorts have been substituted for 

 iron, as the latter were found to be much corroded by the sulphur escaping, and the use of lime 

 omitted altogether, thus entailing a much higher heat, and, as wood is not plentiful, an increased 

 expense. Mr. Halleck thinks that, owing to the difiiculty about obtaining and repairing iron 

 works there, that the balance is in favor of clay retorts and excessive heat, as the use of lime 

 is prohibited in clay vessels on account of its fluxing the retorts ; the whole of the cinnabar is 

 never reduced by heat alone, and owing to the high temperature, both the vapor of metallic 

 mercury and some of the sulphuret escape decomposition, are volatilized, and pervading the 

 atmosphere of the works produce the usual symptoms of poisoning by mercury, as salivation, 

 paralytic tremblings, and disease of the brain, terminating in insanity, which symptoms are 

 only exhibited in the hacienda. 



There is no doubt that by proper management of the furnaces these mercurial poisonings might 



