In combining these experiments, Mr Canton found, that water was more compressible in winter than in summer, while, on the contrary, alcohol and oil of olives were more compressible when expanded by heat, and less so when contracted by cold. The results were, as expressed in the following Table, suited to the mean weight of the atmo sphere.
The following Table contains all the results which Mr Canton obtained. It is suited to a temperature of 50° of Fahrenheit, and to 294 inches of the barometer.
From these results it appears, that the compressions are not, as might have been imagined, in the inverse ratios of the specific gravities. If the law of compression in water is the same as that in air, it would follow, that, at a depth of 100 miles, the density of the water would be doubled, and at the depth of 200 quadrupled.
In the year 1774, the Ex-Jesuit Herbert published at Vienna a treatise, entitled De ?guce Elasticitate, in which he confirmed the general result of Canton's experiments, and in 1779 M. Zimmerman published an accotint.of simi lar experiments at Leipsic, under the title of Traite de l'Elasticite de ?eau et d'autres fuides. He found, that sea water, when inclosed in the cavity of a strong iron cylinder, and pressed by a force equal to a column of sea water 1000 feet high, was compressed part of its own bulk, a result much greater than we should have expect ed from the experiments of Canton. A number of results similar to these were obtained by the Abbe Mongez, who has printed an account of them in the 9th volume of Ro zier's Journal.
As the doctrine of the compressibility of water has long been considered as a fact rigorously established, we were surprised to find its incompressibility stated by the Abbe Hauy, without the slightest reference to any of the preceding experiments. " One of the experiments," he observes,
" which has served to chew the incompressibility of water, consists in charging that liquid with a column of mercury, by employing a bent tube in the form of a syphon, the shortest branch of which is closed at its superior part, and contains water, at the same time that the longest branch is occupied by the mercury, which presses the surface of the water. The column formed by this latter fluid was not shortened by the smallest perceptible quantity, even when that of the mercury was 227 centimetres, or about seven feet high, in which case it exerted upon the water an effect triple of that of a column of water 33 feet high.'" In this experiment, which must have been carelessly made, the compression ought to have been thrice as great as in the experiments of Canton.
Fluids have also been divided into perfect and inzper feet ; but this division is quite arbitrary, as there is no body which possesses the character of perfect fluidity. Boiling water approaches nearer to a state of perfect flu idity than water in any other state. As its temperature diminishes, its viscidity increases, and its fluidity becomes less perfect. In many of the oils, varnishes, and in melt ed glass, the fluidity is extremely imperfect ; whereas it may be considered as nearly perfect in water, alcohol, mercury, &c.