596 Messrs, W, and R. PhiUips on [Apeil, 



exchange of momenta takes place, C. concluded that if an 

 absolutely cold body were brought to touch a warm one, no 

 matter how great its temperature, the hot body would become 

 absolutely cold, and the cold one would become as hot as the 

 other was ; and this, 1 believe, is to hold good whether the 

 bodies have an equal or an unequal number of particles. Hence 

 if the cold body should contain a greater number of particles 

 than the hot one, motion must, to an indefinite extent, be gene- 

 rated by the mere contact; and if the cold body contain a less 

 number, motion must by the same means be indefinitely 

 destroyed. It is impossible to tell when one considers these 

 ridiculous conclusions what we ought rather to do — to smile at 

 the folly, or to pity the absurdity and presumption of the man, 

 who could thus venture to utter to the world such things as the 

 legitimate consequence^ of a theory, supported by Bacon, Des 

 Czu'tes, and Newton ! ! 



I have now shown, so far as C.has objected to it,thatthe theory 

 of heat by motion is not incompatible, but perfectly compatible, 

 with phsenomena. He that desires to see the theory amply and 

 fully expounded, may consult Mr. Herapath's last paper in the 

 Annals, from July, 1821, to January, 1822. It will there be 

 found that Mr. H. has not clothed his theory in the deceitful 

 garb of general reasoning, but has reduced it to mathematical 

 and numerical laws ; and has defended the whole by a phalanx 

 of facts, which it would, perhaps, put even the confidence of C. 

 to the blush to oppose. 



( To he concluded in our next.) 



Article VI. 



On the Crystalline Form of Yellow Copper Ore. By William 

 Phillips, FLS. &c. JVith an Analysis. By Richard Phillips, 

 FRS. L. and E. &c. 



Yellow copper ore occurs in Cornwall in different states; 

 namely, crystallized, amorphous, and mamillated, the latter 

 variety sometimes passing into botryoidal and stalactitic. 



Every mineralogist, beginning with Rome de Lisle, has to the 

 present time considered the ordinary crystalline form of the 

 yellow copper ore to be the regular tetrahedron, which also has 

 been assumed to be the primary form of its crystals, except by 

 Mohs, who considers it to be an octohedron, with a square base, 

 and who notices cleavages parallel to its planes. 



I have for several years been in possession of regular cleavages 

 of this substance with perfectly brilliant planes, and even of the 

 primary octohedron produced by cleavage, without, however. 



