86 
FIRST REPORT- 1831. 
according to Robertson’s experiments at 0*9, Mr. Dalton ob¬ 
serves that the mean specific gravity of all the solids and fluids 
which are in it is about 1 *05. The air contained in the lungs 
and other receptacles of the body is estimated at 150 cubic 
inches; the average bulk of the body 4500 cubic inches, of 
which consequently 4350 cubic inches are solid and liquid 
parts. The mean specific gravity of these parts, taken sepa¬ 
rately when dead, being T05, their total weight should be 
equal to 4567 cubic inches of water; but it was found by actual 
weighing, when alive, equal to 4044 cubic inches,—a difference 
of weight equal to 52o cubic inches of water, or more than Jth 
of the whole weight of the body. The general conclusion de¬ 
duced by Mr. Dalton from these data, combined with other 
considerations, is, that the whole substance of the body is per¬ 
vious to air, and that a considerable portion of air constantly 
exists in the body during life, subject to increase and diminu¬ 
tion according to the pressure of the atmosphere, in the same 
manner as it exists in water: and further, that when life is ex¬ 
tinct, this air in some degree escapes and renders the parts spe¬ 
cifically heavier than when the vital functions were in a state of 
activity. (This Paper has since been printed in the Manchester 
Memoirs , Vol. V.) - 
Mr. Allan communicated a Notice of a magnificent spe¬ 
cimen of aqua-marine in the possession of Don Pedro. 
The largest mass of precious beryl known to mineralogists is 
an aqua-marine belonging to Don Pedro; it is nearly as large 
as the head of a calf, its extreme length being 9^ inches, its 
breadth 6-§ inches; it weighs 225 ounces Troy, or eighteen 
pounds nine ounces. On one side there are slight indications 
of the plane of a crystal; but it is otherwise entirely water- 
worn. Its surface is consequently dull; but beneath it the 
mass is perfectly clear and transparent, and, large as it is, 
without a flaw. It is of a beautiful pale bottle-green colour. 
Mr. Robison, Secretary of the Royal Society, Edinburgh, 
described and illustrated by diagrams the principles and mode 
of construction of his Linseed Oil Barometer , and detailed the 
mechanical processes by means of w hich he had been enabled 
entirely to free the oil from atmospheric air and other gaseous 
admixtures. 
Mr. Forbes read to the Meeting his Essay on the Horary 
Oscillations of the Barometer near Edinburgh. 
In the former part of this communication, the Author, after 
a short view of the progress of his researches on this subject, 
