IOWA ACADEMY OP SCIENCES. 
47 
No. 1. No. 2. 
Weight of powder 5882 gram. .4559 gram. 
Si O 2 found 95.53% 96.14% 
AI 2 O 3 plus traces of Pe 2 O 3 - 4 59% 4.01% 
Total - 100.12 100 15 
The force of adhesion to a wet surface was estimated at 200 
grams per square centimeter, or about one -fifth of an atmos- 
phere, but it may be much greater. If applied to a poisoned 
wound at once it would undoubtedly absorb some of the poison 
and so assist in the cure. The popular belief in its efficacy has 
therefore, some foundation in fact. 
If more of this rock can be secured it is our intention to test 
the rapidity of its absorption of moisture from the air when cut 
in thin slices, with a view to its use as a hygrometer. 
The vein in which the specimen was found is twenty feet 
wide, nearly vertical, and strikes westward. The contents of 
the vein are chiefly light and dark blue translucent quartzite, 
mixed with amorphous clay and iron oxide, and bordered by a 
thin blanket of limestone. Some of the translucent quartzite 
is mixed with light gray mad stone, as if the firmer portions 
were formed by fusion of the light gray material. The latter 
agrees very closely in composition, as well as in appearance, 
with the siiicious shells already mentioned, and was probably 
formed from them by the internal heat of the vein. 
PHYSICAL THEORIES OP GRAVITATION. 
T. PROCTOR HALL. 
A force which belongs to individual atoms, is independent 
of chemical and physical conditions, and cannot be altered or 
destroyed by any known means, must be closely related to the 
fundamental nature of the atoms. One of the most essential 
parts in our concept of matter is mass, and the force of gravi- 
tation of an atom is proportional to its mass. Mass and gravi- 
tation stand, therefore, either as co-efiects of the same cause or 
as cause and effect. The force exerted by each atom at any 
point decreases in proportion to the increase of the expanding 
