96 
cially constructed machines capable of de- 
veloping pressures reaching nearly 100 tons 
to the square inch. 
Under high pressures the marble was 
found to flow, bulging out the iron tube that 
enclosed it on allsides. When the iron tube 
was cut away a solid block of marble was 
obtained, which had completely altered its 
shape. It was found, however, that the 
marble in these cases was only about half 
as strong as the original rock. 
Other columns of marble were then heated 
to temperatures of 300 C. and 400 C. and 
while thus heated the pressure was applied 
as before. Under these conditions the rock 
was found to flow readily and to retain its 
strength much better, being nearly as strong 
as the original rock. 
In the third series of experiments the 
marble was not only heated to the tempera- 
tures before mentioned, but at the same 
time water under a pressure of 460 pounds 
to the square inch was forced through it 
while it was being compressed. Under 
these conditions, the marble after being 
molded was found to be as strong as it was 
originally. 
A microscopical study of the structure 
of the deformed marble shows that in these 
two latter cases the crystalline grains com- 
posing the marble had glided on one an- 
other. 
This structure is exactly the same as that 
which is produced in a billet of iron when 
it is heated and then hammered or rolled, 
or in a button of gold when flattened in a 
vise, so that the marble flows just as any 
metal does when submitted to pressure, ex- 
cept that under the ordinary conditions at 
the surface of the earth the brittleness of 
the marble causes it to break before the 
flow point is reached. In the depths of the 
earth, however, being hemmed in by other 
rocks, it flows as in the experiments. 
The paper was elaborately illustrated by 
specimens and by many lantern slides, show- 
SCIENCE. 
[N. S. Vou. XIII. No. 316. 
ing the machines employed, as well as the 
marble before and after compression. They 
also illustrated its structure as compared 
with that of various rocks found in the 
earth’s crust and with hammered iron. 
In discussion B. K. Emerson asked (1) 
whether the cylinders of marble contained 
any water before they were put into the 
machine; (2) if any schistosity resulted, 
and, if so, in what way it was related to the 
optical properties of the calcite grains; (3) 
if the marble rebounded on the release of 
pressure. 
J. EK. Wolff inquired whether the water 
that was forced in passed around or through 
the cylinder of stone, and if solution played 
any part. 
G. K. Gilbert asked if the speaker could 
draw a parallel between the pressures em- 
ployed and the depths within the earth cor- 
responding to them. 
In reply Professor Adams stated (1) that 
the cylinders of marble were kept in a per- 
fectly dry laboratory, and that while no 
determinations of their content of water had 
been made, they were practically dry when 
put in the machine; (2) he had noted no 
rebound. The marble was first compressed 
and then accommodated itself to the pres- 
sure by flowage; (3) he had been unable 
to note any effects of solution as a result of 
the entrance of the water. The results 
were the same with or without the water, 
except that with the water the resulting 
disk was stronger. The water entered at 
the top under 460 pounds’ pressure to the 
square inch and emerged at the bottom. 
The water had dissolved a little copper 
from the tube of entry, which was precip- 
itated on the bottom of the marble. He 
could not state positively whether it went 
through or around, but the marble was ina 
bath of vapor. 
J. E. Wolff suggested that waters with 
some dissolved dye or easily reducible salt 
be employed so that the last point could be 
