Brown Lead Ore of Zimapan. 439 



needles formed by ammonia, they became a most beautiful red without losing 

 their form, and they melted afterwards into an opaque mass, between liver- 

 brown and lead grey, with very fine stars on the surface, of a semi-metallic 

 lustre, its weight 11.75 gr. I put it into the forge in a small crucible 

 with charcoal, for an hour and a half; the mass became only black with 

 charcoal, and the increase of weight was 1.25 gr. I put it into a small re- 

 tort with nitric acid, red vapours were formed at last, and the matter was 

 red. I repeated the same twice, and I augmented the fire in the end, to 

 disengage all the nitric acid : on pouring some water on it, it became emul- 

 sive or milky. The emulsion being cleared off" at length, it did not redden 

 the tincture of radish, though it precipitated, with a yellow colour, the solutions 

 of nitrate of silver, mercury and lead : it precipitated also prussiate of lime 

 of an emerald green, and tincture of galls of a blackish green. The olive 

 green sediment became immediately red with some nitric acid, and the 

 yellow solution with zinc and iron gave a green oxide. 



" By the blow pipe the glass became grass green. I could not amalga- 

 mate with mercury its combination with ammonia. [Other experiments 

 •which I made at the time were not inserted in my translation.] 



"The proportion then of the constituent parts of the brown lead ore, are 

 80.72 of yellow oxide of lead, and 14.80 of the new substance, the rest be- 

 ing a little arsenic, oxide of iron, and muriatic acid. 



^'^ Presuming that it was a new substance, I called it Pancrome, on ac- 

 count of the universality of the colours of the oxides, solutions, salts, and 

 precipitates : and afterwards Eritrone, on account of its singular property of 

 forming with the alkalies and the earths, salts which became red at the 

 fire, and with acids; but being informed that the chrome gives by evapora- 

 tion red and yellow salts, I believe that the brown lead ore is a yellow oxide 

 of chrome, combined with an excess of yellow oxide of lead." 



Slight deviations sometimes occasion great inconveniences. 

 If the justly celebrated Baron Humboldt, to whom, when in 

 Mexico in 1803, I gave a French copy of the preceding ex- 

 periments, had thought them worthy of publication, they would 

 have excited, doubtless, the curiosity of European chemists, and 

 of Descotils himself, who had more knowledge than myself 

 of the properties of chrome; so that thirty years would not 

 have elapsed before the new metal was acknowledged. Hum- 

 boldt, apparently, did not think so ; because, as I have said 

 somewhere else, European monopolists have not always ap- 

 peared solicitous to sustain the merit of discoveries effected in 

 the Americas. 



I am quite astonished to hear that Kersten has analysed the 

 brown lead ore of Poullaouen and found it to be phosphate of lead. 

 I determined that of Zimapan to be brown lead ore, only by its 

 external characters, which were entirely identical with those 



