APPENDIX. 
341 
No. 155.— Bituminous silica.—San Pedro. 
A hard black silicious rock. Heated in a tube closed at one end gave a distillate of bitumen 
and water. Fused with soda on charcoal yields a hepar of sulpburet of sodium. 
The finely-powdered mineral was fused with carbonic of soda and silica, separated in the 
ususl way. The acid solution contained— 
Alumina and oxide of iron. 
Oxide of manganese trace. 
Lime, inconsiderable quantity. 
Magnesia. 
Sulphuric acid. 
Phorphoric acid. 
The presence of fluorine could not be detected. The presence of notable quantities of soda 
and potash was detected by Smith’s process of fusion with carbonate of lime and sal ammonise. 
The infusorial (animal) origin of the rock is beyond a doubt. 
No. 162.— Clay from the bank at the Alamo Well , Colorado Desert. —The aqueous extract con¬ 
tains— 
Chloride of sodium. Carbonic acid. 
Lime, (carbonate.) Sulphuric acid, (trace.) 
Magnesia. 
The acid extract contains beside these, alumina and oxide of iron, and a trace of potash. 
No. 204.— Limonite, {Mariposa.) —Limonite—a hydrated peroxide of iron, containing traces 
of silica, lime, and magnesia. No sulphur. 
No. 250.— Travertine, from Pilot Knob. —The finely-powdered and dried mineral was dissolved 
in hydrochloric acid, the insoluble residue of silica separated by evaporation, and afterwards 
fused with carbonate of soda, by which a considerable quantity of alumina was separated from 
it. The acid solution filtered from the silica was accurately divided by measure into two equal 
parts, from one of which sulphuric acid was precipitated by chloride of barium. The other 
portion was treated with ammonia, and the precipitated oxides washed by decantation till only 
ytoo °f the original salts remained in the water. Alumina was then separated by potash, and 
precipitated by hydrosulphuret of ammonia. The oxide of iron was ignited together with the 
filter on which it was washed, re-dissolved in acid, and a minute residue of silica filtered off. 
The solution was neutralized by ammonia, the precipitate of oxide of iron filtered off, and the 
filtrate added to the first filtrate from alumina and iron. Lime was precipitated as oxalate 
and weighed as carbonate. The filtrate from the lime was evaporated to dryness and ignited, 
magnesia removed by caustic baryta, the excess of baryta by sulphuric acid, and the residue of 
sulphate of soda ignited and weighed. Carbonic acid was estimated by loss; chloride and 
magnesia were estimated in separate weighed portions. Fluorine was sought for without suc¬ 
cess. The analysis gives as the composition of the mineral— 
Silica. 9.10 
Lime... 48.08 
Carbonic acid___ 37.63 
Magnesia_ 0.52 
Alumina_ 2.085 
Oxide of iron_ 1.106 
Soda. 1.81 
Chlorine_ 0.02 
Sulphuric acid... 0.19 
Phosphoric acid.. trace. 
100.541 
