Dr. Genth’s Contributions to Mineralogy. 167 
from 76° F., ae - in 2° 39 north, 91° 58’ west (of Green- 
wich), to 81-9° F., in August 31, 11° 15’ no orth, 107° 3’ west, 
after chiab it was si above 80°F. The same place i in the ocean 
which gave Vaillant 76° F., in August, afforded Fitzroy (4° 
north, 96° west), on March 26 (when the sun had long been far 
north), 823° F. This fact shows the variations of temperature 
that take place with the change of season 
(To be continued.) 
Arr. X VII.—Conitributions to Mineralogy ; by Dr. F. A. Gentu 
of Philadelphia. 
(Concluded from p, 86.) 
5. Owwenite,a new mineral.—I found this mineral in the meta- 
morphic rocks on both sides of the Potomac River near Harpers 
Ferry, associated with quartz and sometimes with impressions of 
carbonate of magnesia. 
Massive, aggregate of minute scales; cleavage distinct in one 
direction; H. =2°5; Sp. gr. =3-197 (at 20° C. ); color olive- 
green ; streak paler; lustre pearly ; fracture subconchoidal; very 
tough ;. powder greasy to the touch; odor argillaceous. 
BB. ‘fuses easily =3, and gives an iron black magnetic globule ; 
with borax gives the reactions of iron, and with soda in the oxyd- 
ating flame shows the presence of a trace of manganese. Yields 
water in the matrass.: Dissolves readily in dilute hydrochloric acid. 
It was analyzed under my opine oo by Mr. Peter 
pes who obtained the following re 
18920 grammes ignited for = Nei forty-five minutes at a 
sets red hese in a well covered platinum crucible, lost 0'2050 grs, 
. 1:1542 grs. treated in the same manner, lost 0°1195 grs. 
It is possible, that these determinations of water are a little too 
low, because a small quantity of iron was found to have oxydized 
higher on heating. 
TIL. 2:0770 grs. were dissolved in hydrochloric acid. The 
silicic acid gelatinized on evaporation ; it was evaporated to dry- 
ness, the dry mass moistened with hydrochloric acid, diluted with 
water and filtered after it had completely settled. The silicic 
acid weighed 0°4798 grs 
The filtrate was oxydized by nitric acid, Eabeiiabo by am- 
monia, redissolved in acetic acid and evaporated in a water-bath, 
again ‘moistened with water and this ve asin until all 
the acetates of alumina and iron were thus Both 
were filtered, and alumina separated from the sesquioxyd of iron 
by caustic potash in the usual manner. From the acidula 
potash solution the alumina was igre 2 ae by sulphid of am- 
monium ; it gave 03226 gramme 
