dds 



ON MR. PALTOK 8 PRINCIPLE OF COMBINATION* 



proceed upon the same principles as in other case^?, 

 Now what is generally aasitrned as the cause of the different 

 specific gravities of bodies? Why is a cube of lead heavier 

 Causeofspe- than a cube of ivory? The most natural answer to this 

 cific gravity, question is, that^ the particles of lead are nearer together, 

 and therefore a greater number of them will be contained 

 in anytjiven space. Whether this difference in proximity 

 be occasioned by interposed caloric, or any power of repul- 

 sion, independent of caloric, it is not our business to inquire. 

 Now if we endeavour to form a conception of a single parti- 

 cle, or what has been denominated an atom, as a substance 

 not made up of any smaller parts, and which cannot there- 

 fore be under the influence of any repulsive power, so far 

 as its individual existence is concerned, it follows that atoms 

 of all kinds must have the same specific gravity. If then 

 they differ in their weight, there must be a corresponding 

 difference in their size, an atom of oxigen for example must 

 be 7 times as large as an atom of hidrogen ; but were this 

 the case it could scarcely be regarded as an atom, but as 

 a substance of considerable extent, capable of being di- 

 vided into still smaller parts. 



These observations, it is obvious, are entirely conjectural, 

 and I have only brought them forward, to meet conjec- 

 tures on the other side of the question. My object in this 

 paper has been to point out the insufficiency of Mr. Dal- 

 ton's hypothesis, without attempting to substitute another 

 in its place ; for important as the object is which he has en- 

 deavoured to accomplish, and ingenious as the attempt may 

 appear, I am decidedly of opinion, that we have not yet a 

 J*** sufficient basis of facts, &n which to erect so capacious a 



^.. superstructure, 



T am, Sir, yours &c. 



J. BOSTOCK. 

 Knot'shole Bank, near Liver pooh 

 Feb.^^d, 19H, 



VIl. 



