. ae 
ee ee vf a al 
S. W. Johnson on some points of Agricultural Science. 71 
until we reached the plain, and it would seem that none are 
formed except where the descent is but little, or the lava but 
imperfectly melted. 
here is only one point more of which I will speak. I am 
not quite satisfied that there is a fissure in the side of the moun- 
tain, through which the lava made its exit to the surface. Those 
of our party who had seen the flow of 1840 and who had no 
doubt of a fissure in the side of the mountain then, think that 
there is no fissure in this case. 1 do not of course believe in the 
old theory of a perpendicular duct or pipe reaching down to the 
reservoir of lava, but it seems to me that the lava by the pres- 
sure of gases and steam works its way to the surface as the water 
of springs by hydraulic pressure. draulic pressure also con- 
stitutes a part of the force which impels lava. Mauna Loa is 
full of caves, passages, &c., and very porous, and besides the 
lava, in case of this flow at least, could melt its way more or 
less, where it met obstructions. It may be, however, that there 
is a rent in the side of the mountain. 
Norse.—We have received from Prof. Alexander of Honolulu a map 
giving the course of the lava, and enabling us to make a correction in the 
map published in the last number of this Journal. The course there 
given was copied from the “Commercial Advertiser” of Honolulu. It 
requires only that the current should be made to flow west-north-west 
from near its point of starting, and then on reaching the base of Hua- 
lalai, bend northwestward into the course given in the map.—Eps, 
Art. IX.—On some points of Agricultural Science; by SAMUEL 
W. JoHNsON, Professor of Analytical and Agricultural Chem- 
istry in the Yale Scientific School, and Chemist to the Connec- 
ticut State Agricultural Society. ‘ 
The Absorptive properties of Soils—It has long been vaguely 
known, that the soil possesses a remarkable power of absorbing 
a great variety of bodies. How the soil absorbs odors (more 
them in a state of comparative om from offensive odor.* 
* It is well known that some surfaces have a r power of attaching 
odors to them than others. Every has observed that woolen garmen 
ich a cloth is dyed affects its rctentiyeness for some odors, It is a fact, as the 
