ON COHESION. 473 



**( 

 with a variable repulsion is also observable in the force of cohesion ; and 



supposing two particles of matter, floating in such an elastic medium, 

 capable of producing gravitation, to approach each other, their mutual 

 attraction would at once be changed from gravitation to cohesion, upon the 

 exclusion of the portion of the medium intervening between them. This 

 supposition is, however, directly opposite to that which assigns to the elastic 

 medium the power of passing freely through all the interstices of the ulti- 

 mate atoms of matter, since it could never pass between two atoms cohering 

 in this manner; we cannot therefore, at present, attempt to assert the 

 identity of the forces of gravitation and cohesion so strongly as this theory 

 would allow us to do, if it could be established. In short, the whole of our 

 inquiries respecting the intimate nature of forces of any kind, must be con- 

 sidered merely as speculative amusements, which are of no further utility 

 than as they make our views more general, and assist our experimental 

 investigations. 



LECT. XLIX. ADDITIONAL AUTHORITIES. 



Bernoulli, De Gravitate ^Etheris, 12mo, Amst. 1683. Newton's Optics ; Queries. 

 Huygens, Op. Rel. i. Hambergerus, De Experimento Huygenii, 4to, Jena, 1723. 

 Hausen, Programmata de Reactione, Leipz. 1740. Richmann on the Force of Water 

 in Freezing, Nov. Com. Petr. i. 276. Keill's Introd. Lect. viii. Golden on the 

 Primary Cause acting on Matter, 1745. Knight on Attraction, &c. 4to, Lond. 1748. 

 Hollmann, Commentationum Sylloge, 4to, Gott. 1764-1784. Bossut sur la Resist- 

 ance de 1' Ether, 4to, Charleville, 1766. Van Swinden, De Attractione, 4to, Leyd. 

 1766. Kratzenstein, Amolitio Vis Inertise, Hanov. 1770. Franklin's Miscellanies, 

 4to, Lond. 1779. Zimmermann, Traitedel'Elasticite de 1'Eau et d'autres Liquides, 

 Leipz. 1779. Coulomb on the Force of Torsion, Hist, et Mem. 1764, p. 265 ; 1784, 

 p. 229. Delangez on the Mechanics of Semi-fluids, Mem. della Soc. Ital. iv. 329. 

 Mossotti on Molecular Action, Scientific Mem. i. 448. Kelland on do. Camb. Tr. vii. 



Atomic Theory. Higgins, Comparative View of the Phlogistic and Antiphlogistic 

 Theories, 1789. Wenzel, Lehrevon der Verwandschaft derKbrper, 1777. Richter, 

 Anfangsgriinde der Stochyometrie, 1792. Dalton's New System of Chemical Phi- 

 losophy, Manch. 1808, 1810. Avogadro, Mem. di Torino, xxvi. 440, xxviii. xxix. 

 30, xxxi. xxxiii. Mem. della Soc. Ital. 1822. Fisica dei Corpi Ponderabili, 2 

 vols. Torino, 1837-8. Daubeny's Introduction to the Atomic Theory, Oxf. 1831. 

 Thomson's, Turner's, and all Treatises on Chemistry. 



LECTURE L. 



ON COHESION. 



THOSE properties of matter, which we have lately examined, if they are 

 not absolutely inseparable from its constitution, are, at least, always 

 found attached to such matter as we are able to submit to our experi- 

 ments. There are, however, many other general affections, to which all 

 matter appears to be liable, although none is perpetually subjected to 

 them, and these are principally, if not entirely, dependent on the force of 

 cohesion. 



