. 
180 Foreign Literature and Science. 
24. Saltpetre.—It is stated by Henri Braconnot, that the 
stem and leaves of the common Beet when dried and burn- 
ed, yield ashes so rich in alkali, that it melts easily by heat, 
and surpasses many of the commercial varieties of potash. 
Beets which grow in a soil highly manured contain much ni- 
e; those which grow in thin and sandy soils, very little. 
The leaves of the former when tied in bundles, and hung 
up to dry in places slightly moist, warm, and rather dark, 
will have their leaf stalks entirely penetrated and covered 
with an innumerable multitude of small crystals of saltpetre. 
The nitric acid, in this case must have entirely displaced the 
oxalic and malic acid, Js this acid formed under the influ- 
ence of the animalised substance contained in the petioles, 
or is it produced exclusively by the elements of the atmos- 
phere? The author tried in Conjunction with a friend, to 
manufacture saltpetre from the residue of the beets used in 
a sugar factory but was not successful.—Ann, de Chimie, et 
de Physique, Juillet, 1827, : 
25. Evaporation of water from hot surfaces.—It was as- 
certained by Lerpenrrosr, in 1756, that between the_boil- 
ing point and that at which iron becomes white hot, water 
evaporates from its surface less easily the greater the heat. 
Klaproth repeated these experiments and relates the result 
as follows. 
let fall another, and then a third, fourth, &c. the spoon cool. 
g the whole time. 
~The first drop continued 40 seconds, 
the’second == =. «90 
third = Ronee . a 
fourth = 4, & 
th — 
I 
~ Having let fall seven drops in a spoon heated to the prop- 
*t point, they united in a ee mass which began to turn 
is with rapidity. It afterwards separated at the top, 
i : 
give = 
