118 Rev. J. B. Emmett om Capillary Attraction. 



The quantity of the depression in the above experiments is 

 not to be regarded as I'igidly accurate, since the apparatus 

 employed is imperfect: the future experiments (of which you 

 will receive an account in time for your next Number,) will be 

 made with an apparatus in which the index will be moved by 

 means of a fine micrometer-screw : the above, however, prove 

 unquestionably that heat depresses water, and some, probably 

 all, other liquids.* 



It would be premature to assign the cause to which these 

 phaenomena are to be ascribed : yet since the diminution pro- 

 duced in the density of the liquid by heat, cannot give rise to 

 the effect f, it appears highly probable that the repulsive 

 force of caloric, acting between the solid and the particles of 

 the liquid %, being augmented by an increase of temperature, 

 the sensible force of attraction, ?. e. the excess of the attrac- 

 tion above the force of calorific repulsion is consequently di- 

 minished, and therefore the height of the suspended column 

 is reduced. 



Should this be the case, the phaenomena of capillary attrac- 

 tion will afford a ready and accurate means of ascertaining the 

 relative intensity of the attraction of various bodies, and the 

 ratio between the force of attraction, and that of repulsion at 

 different temperatures, together with many other departments 

 of chemical science. 



[To be continued.] 



* If the conjectured be the true cause of the phaenomenon, mercury also 

 will be depressed by heating the tube. 



\ For, let A be the density of the liquid, when cold ; a, that when 

 heated; H the altitude of the cold, and h that of the hot column. AH 

 will be the pressure upon a given area, when cold; and ah, that when hot. 

 The attraction of the glass is equal to this pressure : this attraction is pro- 

 portional to the density of the liquid (the liquid being the same in dif- 

 ferent states of density); i. c. in the cold, to A, and in the hot to a; or 

 AH:a/;::A:a; therefore whilst the density of the liquid is changed by 

 the application of heat, the altitude of the suspended column remains con- 

 stant. 



J That the particles both of liquids and gases attract those of solids, 

 and that the force of repulsion of caloric acts mutually between them, may 

 be proved in several ways. Oxides of manganese, iron, lead, silver, mercury, 

 and many other metals, are either wholly or in part reduced by the appli- 

 cation of heat; so are most carbonates, some muriates, all nitrates. Now 

 the fact of their combination proves that the particles of the solid attract 

 those of the gas ; and that of the decomposition, that they mutually repel 

 each other by reason of their calorific atmospheres; in like manner water 

 combined with snbcarbonate of soda, sulphate of soda, borax, and many 

 similar bodies, even being equal in weight, in some cases, to the dry matter, 

 forms with them dry solid crystals : hence it is retained by a powerful force 

 of attraction : the application of heat first fuses the crystals, then evapo- 

 rates the water : hence the repulsive force of caloric is mutual between the 

 particles of a solid salt and the water of crystallization. 



XXVII. A new 



