1852.] 113 



A portion of the alcohol (reacting acid like the honey) neutralized by caustic 

 potassa, then distilled with sulphuric acid, gave an aqueous acid liquid, which, on 

 addition of nitrate of silver, gave a whitish precipitate, becoming black on boil- 

 ing, rendering the supposition of formic acid probable. 



The Committee on the two papers by Dr. Genth, entitled respectively 

 ^^On some Minerals which accompany Gold in California,^^ and ^' On 

 Strontiano-Calcite, a new Mineral/' reported in favor of publication in 

 the Proceedings. 



On some Minerals, wJdch accompany Gold in California. 

 By Dr. F. A. Genth. 



A few days ago I had an opportunity of examining a lot of Gold from the north 

 fork of the American River, 30 miles from Sacramento City. 



The gold was in very fine scales and but a few larger pieces among them. 

 The following minerals have been found mixed with it, viz. : 



1. Hyacintli in almost microscopic crystals, of different lengths. The longer 

 ones exhibit the form of the primitive square octahedron combined with the 

 second square prism ; the shorter ones have besides, a second octahedron, a 

 double eight-sided pyramid and the first prism ; one of the crystals I found having 

 a basal plane besides. They are colorless or show a smoky tinge; only a few 

 less perfect crystals have a grayish-brown color. Lustre perfectly adamantine. 



2. Chromic Iron in rounded grains, which sometimes show faces of the regular 

 octahedron. Color between jet-black and iron-black. Lustre submetallic. 

 Streak brown. Not magnetic. Before the blowpipe with borax it gives in both 

 flames emerald-green beads. The powder was decomposed by bisulphate of 

 potash, and the presence of sesqui-oxide of iron and chromium likewise ascer- 

 tained in the moist way. 



3. Ilmenite occurs in iron-black grains, which show sometimes distinctly a 

 basal cleavage. Lustre submetallic. Streak brownish, and iron-black. Before 

 the blowpipe it gives a blood-red bead, which, when saturated, can be easily 

 enameled. The powder is easily decomposed by bisulphate of potash; the fused 

 mass dissolves completely in diluted hydrochloric acid, and this solution, when 

 evaporated, lets fall a white powder, which gives with borax and microcosmic 

 salt the characteristic reactions of titanic acid. The solution in hydrochloric 

 acid contains nothing but sesqui-oxide of iron. 



[Both Chromic Iron and Ilmenite seem to have been confounded with magnetic 

 iron.] 



4. Platimim. A few steel-colored rounded grains were observed, and of 



5. Iriclosmi7ie, a few lead-colored scales. The quantity of both Platinum and 

 Iridosmine was too small for further examination. 



I will mention here, that I have examined some white grains and scales from 

 Stanislaus in California, which were presented to me by Prof. John Frazer, 

 whose brother had them collected. 



The few scales of gold mixed with them were extracted by diluted aqua regia. 

 I then treated them with concentrated aqua regia as long as it acted upon. 



The solution contained almost pure bichloride of platinum with but a trace of 

 iridium ; neither rhodium nor palladium could be detected in it. 



The residue consists of six-sided scales of a color between lead- and tin-white. 

 On heating them upon platinum foil, they give out a strong odor of osmium ; they 

 are therefore the combination Ir Os4 (or Ir OS3) known under the name of Sis- 

 sershite. Being heated thus, most of the scales become iridescent and assume, 

 like steel, yellow, orange and blue eolors. I do not know that this reaction has 

 been observed. In. order to ascertain whether every kind of iridosmine gives it, 



