Mineralogy and Geology. 119 
II. Mrneratocy anp GEOLOGY. 
1. Analysis of Allophane from the Black oxyd of Copper mines of 
Polk County, Tennessee ; by Dr. C. T. Jackson, Assayer to the State 
of Massachusetts, &c.—Description.—This mineral occurs in the great 
veins of black oxyd of copper of Polk County, Tennessee, encrusting 
the black oxyd of copper, and is especially abundant in the mine 
worked by Mr. Congdon. It occurs in botryoidal and reniform concre- 
tions with a crystalline aspect somewhat resembling concretions of Preh- 
nite in appearance. 
Its color is honey yellow. Lustre resinous, particularly on fractured 
uantitative analysis on 2 grammes of the mineral.—One gramme of 
the mineral heated to full redness in a platinum crucible, loses 0° 
gramme of water. 
One gramme of the mineral that had not been ignited was decomposed 
by chlorohydric acid in a platinum crucible, and then the usual process 
of analysis for the separation of the different ingredients was pursued, 
and the following results were obtained : 
Water, 0377 
= sie 
RS ec. je So BAY BAL crak dis. occ 4 
Magnesia, . g ; : 4 ; 0-002 
P. hosphorie acid, . e : S 3 ‘ traces 
Phosphoric acid 
2. On the Boracie Acid Compounds of the Tuscan Lagoons; by 
Emu Becut, ( Berg- und hiittenmannische Zeitung, Oct. 18, 1854.)— 
Since the publication in the American Journal of Science of descrip- 
ions and analyses of some Tuscan minerals containing boracic acid, 
which had been described and analyzed by Prof. Meneghini and myself 
(as communicated to Prof. Dana by Prof. Meneghini), I have further in- 
vestigated the subject with some new results interesting to mineralogical 
