8 Sketch of the latest Improvements [Jan. 



forces, which are the same as the chemical forces. The first is the 

 combination between the forces themselves; the result of it is the 

 contraction ot the two forces, or their reduction to a smaller 

 volume, wiih the disengagement of light and heat. The second is 

 the combination of a product with a supporter. The result of it 

 likewise is condensation, and the evolution of light and heat, 

 though not to so great an extenc as in the first case. The third 

 degree i-onslsts in the combination of an alkali with an acid. It is 

 rarely accumpunied by the disenga;i:ement of light, but always with 

 the di>engjgemcnt of heat. A condensation hkevvise takes place 

 unless peculiar causes modify the result. Expansion, which is the 

 effect of a repulsive force in bodies, is most frequently owing to an 

 exces; of one of the electric forces. Contraction is the effect of 

 an equilibrium between the forces, and of their mutual extinction. 



'I'he forces which produce the electrical and chemical actions of 

 ])odjes an' the same as those whicii produce the mechanical proper- 

 ties of bodies. Iiiipenetrability depends on the resistance which 

 tlie expansive power of two forces opposes to a body endeavouring 

 to penetrate the space already occupied ijy another body. Cohesion 

 is the eftict of *be two forces, which attract one another. Uni- 

 versal attraction consists in the action at a distance of the two 

 forces upon each other, supposing the expansive power of each force 

 pot to ext. no be ond the surface of bodies. 



■ Sui h is an abstract of M. Oersted's hypothesis, as far as I have 

 been able to make it out. It is fair, however, to state, that 1 have 

 not had an opportunity of perusing his own work, but only the 

 abstracts of it published in some of the German journals, and an 

 outline given by Van Mons in his translation of Sir H. Davy's Ele- 

 mentary Work. Hence it is very possible that I may not have done 

 the author justice, and that some of the parts of his hypothesis, 

 which appear the most whimsical and absurd, would assume another 

 aspect under the explanations of the author himself. On that 

 account I shall not attempt any critical examination of this hypo- 

 thesis, wbich has given the author considerable celebrity in Ger- 

 many. Its weak parts and inconsistencies are sufficiently obvious to 

 those who have followed the late improvements in electricity and 

 chemistry. The metaphysical part I do not fully understand ; nor 

 have I been able to make out whether the author's electrical forces 

 be substances or qualities. 



At present, then, it seems to be tlie prevailing opinion of chemists 

 that fhcniical affinity is identical with electrical attraction. The 

 opinion possesses much plausibility, and even probability; but much 

 remaii s to be done before It can he considered as established, and 

 made tlie Ibundation of our chemical reasonings. 



11. Proportions in icliich Bodies combine chemically. — That the 

 ultimate {jariicles of matter consist of atoms, incapable of farther 

 subdivision, iy an opinion which has been pretty generally received 

 among phil'jiophers ever since the time of the Greeks ; and since 

 tlie Citiiblishmeut of tlie Newtonian philosophy this opinion has 



