ANALYSES OF MINERALS. 25 



nishes water wheu heated in the test-tube, arising from the presence of the hydrated carbonate. The copper was deter- 

 mined as oxide by treating the acid solution with caustic potass. 



In 100 parts : 



Water and carbonic acid - - 4.70 



Oxide of copper - -- 95. 30 



100. 00 

 or yielding TS^Vo P^"^ cent, of copper. =^=: 



No. 3. Brown iron ore. — Ochreous variety ; specific gravity =: 3 ; j-ields but little water in the tube ; effervesces slightly 

 in hydrochloric acid. The iron was determined as peroxide by precipitation with ammonia. 



lu 100 parts : 



Organic (vegetable) matter and water - 7. 80 



Insoluble earthy matter, (clay) - 15. 00 



Peroxide of iron, 70. 70 



Lime 5. 05 



Magnesia ^ _ j i,^ 



Carbonic acid 



100. 00 



Yields 49 per cent, of metallic iron. 



THOMAS ANTISELL, M. D. 



Smithsonian Institution, WasUngUm, March 1, 1856. 



Sib : I have the honor herewith to submit to you the results of the examination of salts, ores, and minerals, made by 

 me for the United States Mexican Boundary Commission. The analyses were made in the laboratory of this institution. 

 The numbers correspond with those attached to the original labels. The ores, though.few in number, are of such a character 

 as to raise high expectations of the mineral wealth which thorough exploration will develope in the region traversed by the 

 commission. 



No. 15. Argentiferous galena, from the copper mines of Santa Rita, in New Mexico. The specimens examined are very 

 fine-grained galena, containing scattered particles and nodules of iron and copper pyrites, with some o.xide of iron, resulting 

 from the oxidation of iron pyrites. One of the specimens contains adherent portions of the gangue from both sides of the 

 vein, showing it to have been, at this spot, 1 to IJ inch in thickness. It yielded 73.75 per cent, of lead. The mean of 

 two accordant assays, by cupellation, gave 0. 365 per cent, of silver. The copper in both this and the following specimen is 

 so unequally disseminated, that it was impossible to obtain a fair average without destroying the specimen. The amount 

 of copper in both ores is small. 



No. 16. Lead ore, from the silver mines of San Pedro, in Chihuahua. The specimens furnished me do not, probably, 

 represent fairly the richness of the mine. They are very imequal In composition and value, consisting of galena, mixed 

 with zinc blende, quartz, iron pyrites, and a little copper pyrites. A sample, which was regarded as affording a tolerably fair 

 average, yielded 28. 29 per cent, of lead. The mean of two assays gave 0. 70 per cent, of silver. 



No. 18. A white saline substance, occurring as an incrustation on the soil, at Salado spring, in Chihuahua. It dissolves 

 in water, leaving only a small residue of white sand, containing calcareous particles. It consists chiefly of chloride of 

 sodium, (common salt,) with a considerable quantity of sulphate of soda, and small quantities of sulphate of magnesia, 

 chloride of magnesium, and sulphate of lime. The presence of nitrates could not be detected. If this salt occurs in suffi- 

 cient quantities, it will prove a very valuable source of supply of table salt, the want of which is strongly felt in this region. 

 The presence of sulphates of soda and magnesia renders it unfit for use in its present state, but it might easily be freed from 

 these impurities by solution and re-evaporation. The sulphate of lime is precipitated, in combination with sulphate of soda, 

 as pan-stone, when the saline solution attains a certain degree of concentration. If the concentration be not carried too 

 far, chloride of sodium crystallizes out almost pure. The mother liquor contains in solution the rest of the chloride of sodium, 

 with sulphate of soda and salts of magnesia. It is highly probable that the springs which deposit this salt, by natural 

 evaporation, contain, in solution, enough salt to be used as salines. The waters might be concentrated to a greater degree 

 by being made to pass over piles of twigs, in graduation houses, as is commonly done in Germany. A great sa\Tng of fuel is 

 thus effected. Analyses of the mineral waters of this country would probably lead to many important economic applications. 



No. 18. Is mCTely the same salt as the last specimen, taken from a depth of six inches below the surface. The propor- 

 tion of sand and gravel in it is much greater, but it shows that the whole soil is impregnated with saUno matters. 



No. 19. Copper ore, from Boca Grande, in Chihuahua. This is a very beautiful and pure specimen of red oxide of copper, 

 intimately mixed with native copper. It is entirely free from sulphurets and earthy minerals. The exterior is partially 

 covered with a thin crust of malachite — green carbonate of copper. This ore yielded, in an assay conducted in the moist 

 way, 94.8 per cent, of copper. A very similar ore has been described by Mr. Blake, as occurring near Altar, inSonora.o 

 The compact subcrystiiUine appearance of this ore gives evidence of a massive deposit. 



* United States Pacific Railroad Survey, (partial route in California,) under tlie command of Lieut. R. S. Williamion, Top. Eng., 1853.' Preliminary 

 report by William P. Blake, geologist and mineralogist, p. 75. 



4M 



