434 E.. W. Hilgard—Soil Analyses and their Utility. 
cleavage, are of considerable size, and furnish excellent speci 
mens for microscopic examination. 
The color of the orthoclase is a delicate flesh-red, which color 
is due entirely to the imbedded crystalline scales of what has 
en supposed to be géthite. The stone itself is translucent . 
and quite colorless. The results obtained in two analyses were: 
ie 2. Mean. 
Silica, 64°80 64°82 64°81 
Alumina, 19°02 19°25 19°02 
Ferric oxide, 0°23 } 0°23 
Lime, 1:29 1°23 1°26 
Magnesia, 0°61 0°58 0°59 
Potash, 15°22 13°38 14.30 
Ign., 26 0°26 0°26 
100°47 
In an analysis of an aventurine oligoclase from Tvedestrand in 
Norway, Scheerer obtained SiO, 61°30, Al,O, 23°77, Fes 
O, 0°36, CaO 4-78, Na,O 850, K,O 1:29. In this the per 
cent of géthite is somewhat greater than in the New Jersey 
orthoclase, but in both cases the extremely small amount. of 
foreign matter which suffices to impart the brilliant aventurine 
character to the feldspar is remarkable. It is worth noting 10 
this connection that all the specimens of sunstone from Kennett, 
ester Co., Pa., in the cabinet of the Stevens Institute, are 
oligoclase, not orthoclase. 
amo 
Art. LIL—On Soil Analyses and their Utility; by Eve. W. 
HrLearp, State Geologist of Mississippi. 
(Read at the Dubuque Meeting of the Am. Assoc. Adv. Sci., August, 1872.) 
secured for myself and my co-laborers the compassionate sym- 
