2GG ANNUAL OF SCIENTIFIC DISCOVERY. 



by sulphuric acid, etclicd the oflass with great readiness and dis- 

 tinctness. The following results were obtained by analysis. No. 

 1 in the wet way, by sulphnric acid : — 



Arsenic acid, . . . 65.10; Quantity of Oxygen .... 19.16 



Alumina, .... 20.G0; " " .... 9.G3 



Ferric oxido, ... 4.78; " " .... 1.44 



Managanous oxide, . 1.30; " ** .... 0.38 



Soda, 11. G6; " " .... 3.01 



Lithia, 0.81; " " .... 0.42 



Fluoriuo, .... undetermined. 



84.33 



Analysis No. 2, made in the dry way, by fusion with carbonate 

 of soda, dissolved in water, acidulated with chlorhydric acid, 

 gave: arsenic acid, 53.22; alumina, 20 09; ferric oxide, 5.06; 

 managanous oxide, 1.28. The low amount of arsenic acid by 

 this determintition, it was thought, might be due to the fact that 

 the soda fusion Was made over a gas-blast lamp, with the possi- 

 bility that a portion of the arsenic acid might have been reduced 

 to arsenious acid, and volatilized ; or possibly to other accidental 

 causes. The small quantity of mineral would not allow of a repe- 

 tition of this analysis. 



An analysis. No. 3, was made, qualitative quantitative, in 

 which only the alkalies were estimated. The resuhs of this was: 

 soda, 11.8(3; lithia, 0.70; — agreeing very closely with No. 1. 

 The alkalies examined with the S2)ectroscope showed only the 

 lines of sodium and lithium. 



The composition and oxygen ratio (nearly 1:3:5), says the 

 professor, " suggest an analogy between the new mineral and 

 amblygonite, a tluo-phosphate of alumina, liihia, and soda," but 

 he thinks the results given are sufficient to demonstrate it to be a 

 new mineral, and, tis he thinks, the only observed native fluo- 

 arseniate. 



Oeolor/1/ of Venezuela. — Since the publications of Baron Von 

 Humboldt, nothing has been contributed to the geology of the 

 south-eastern portion of Venezuela. In his grouping of the moun- 

 tain systems of South America, he groups the entire mountain 

 series of all Guayana into one system, and calls it the Parimi sys- 

 tem. Its rocks are all gneiss or granite, and crystalline, according 

 to his description. 



Our examination of a large portion of the northern mountains 

 shows the presence of other rocks, such as schists of various kinds, 

 taleose rock, limestone, and ilacolumite. A section across the 

 trend of the Imitaca range, at right angles, exhibits for the first 

 miles only crystalline rocks. At San ISIaria, the culminating 

 point of this range, it falls off suddenly on the southward full DOO 

 feet, to the i)lains of Cume. Hornblende schists, with intcrstrati- 

 fied veins of quartz, and bands of syenite and granite, with tal- 

 eose, chloritic and silicious .schists, then obtain for two day.s'jour- 

 ney, until we reach tlic valley of the Yuruari lviv«>r, when' we 

 find limestone, itaeolumite, and greater frequency of taleose 



