32 Proceedings of the American Philosophical Society. 
Mr. Peale exhibited specimens of medals obtained by the process of 
Prof. Jacobi. He stated that Mr. Eckfeldt, of the Mint, had found the 
specific gravity of the copper thus procured, to be as high as that of rolled 
copper, that is, 8.95. 
Mr. Peale also exhibited a diaphragm of parchment, which had been 
used in the battery employed in the process; and upon which metallic 
_ copper had been precipitated. He farther exhibited specimens of metal- 
lic silver, reduced, by a similar process, from the chloride of silver ; but 
remarked, that it was not likely to lead to any useful analogous, result, 
owing to the silver being deposited in a granular state. 
11 3.—The committee, consisting of Dr. Patterson, Dr. Hare, and 
Prof. Bache, to whom was referred.a paper entitled “On a new Principle 
in regard to the Power of Fluids in Motion to produce Rupture of the 
Vessels which contain them, and on the Distinction between Accumula- 
tive and Instantaneous Pressures ; by Charles Bonnycastle, Professor of 
Mathematics in the ee of Virginia,” reported in favor of its pub- 
lication in the Trans f the € Society, which was ordered accord- 
ingly. 
Mr. Bonnycastle’s investigation was suggested by a paper read by Dr. 
Hare, and printed in the Transactions of the Society, entitled “On the 
Collapse of a Reservoir, whilst apparently subject within to great Pressure 
from a Head of Water.” Dr. Hare pointed out the circumstances at- 
tendant upon this curious occurrence, and showed how the vessel might 
have been momentarily relieved from the pressure of the water within, so 
as to make that of the surrounding air efficient in producing the collapse. 
The principal object of Mr. Bonnycastle’s paper is to investigate the pre- 
cise nature and degree of ess forces brought into action in this and simi- 
lar cases. 
The results at which Mr. Bonnycastle arrived, are. stated by him as 
follows :— 
1. It is convenient to distinguish between ieeitantilative and instanta- 
neous loads, or between those which are gradually increased until the 
deflection due to the ultimate load is obtained, and those which commence 
in full efficacy from the initial position of the support. 
2. Within the limits of perfect elasticity, instantaneous pressure pro- 
duces twice the effect of that which is accumulative, whether the result 
be to produce deflection or fracture. 
3. In regard to supports perfectly elastic in one direction, and perfectly 
flexible in the other, instantaneous action, at right angles to the axis of 
elasticity, produces a deflection which is to that of accumulative action 
as 4/4 to 1, whilst the tendencies to fracture are as 4 to 1. But should 
any case occur when the law of elasticity follows an extremely high power 
of the deflection, then the singular result will follow, that the deflections 
are the same, whether the force be exerted from the initial state or the 
— 
Sp ndiine., 
ee 
