pp. 138, 371.
I met at Edinburgh with a case, remarkable as to its extent, of hygrometric action, assisted a little perhaps by very slight solvent power. Some turf had been well-dried by long exposure in a covered place to the atmosphere, but being then submitted to the action of a hydrostatic press, it yielded, by the mere influence of the pressure, 54 per cent. of water.
Fusinieri and Bellani consider the air as forming solid concrete films in these cases.—Giornale di Fisica, tom. viii, p. 262. 1825.
Philosophical Transactions, 1823, p. 161.
Annales de Chimie, tom. xxiv. p. 386.
Philosophical Transactions, 1825, p.440.
As a curious illustration of the influence of mechanical forces over chemical affinity, I will quote the refusal of certain substances to effloresce when their surfaces are perfect, which yield immediately upon the surface being broken, If crystals of carbonate of soda, or phosphate of soda, or sulphate of soda, having no part of their surfaces broken, be preserved from external violence, they will not effloresce. I have thus retained crystals of carbonate of soda perfectly transparent and unchanged from September 1827 to January 1833; and crystals of sulphate of soda from May 1832 to the present time, November 1833. If any part of the surface were scratched or broken, then efflorescence began at that part, and covered the whole. The crystals were merely placed in evaporating basins and covered with paper.
In reference to this paragraph and also 626, see a correction by Dr. C. Henry, in his valuable paper on this curious subject. Philosophical Magazine, 1835. vol. vi. p. 305.—Dec. 1838.
Quarterly Journal of Science, 1819, vol. vii. p. 106.
Quarterly Journal of Science, vol. xxviii. p. 74, and Edinburgh Transactions, 1831.