1815.] An Address to Chemists. 123 



with the atomic theory so well as the rest ; and which of course I 

 have not been able to explain in a satisfactory manner. There are 

 others whose existence is not a necessary consequence of the atomic 

 theory of Mr. Dalton. These, in my opinioi;, prove that there is 

 still something wanting in that theory, and which must be added to 

 it in order to render it more complete. In my memoir On the 

 Cause of Chemical Proportions I have endeavoured to draw the 

 attention of the reader to these difficulties. Mr. Dalton has endea- 

 voured to remove them, but with a levity which 1 did not expect 

 from him, and which appears to me injurious to the science. He 

 begins with pointing out the reasons why he cannot be of my 

 opinion respecting the relative size and form of the atoms, &c. I 

 mu>t observe that at the bottom of every speculation in the exact 

 sciences there always remains something which cannot be verified by 

 experiment, and on which, of course, the imagination is at full 

 lilirty to indulge. The reveries of one man may be more ingenious, 

 more interesting, and more probable,, than those of another ; but 

 the science never gains any thing by disputes about subjects which 

 are not susceptilile of proof. I shall therefore pass over that part of 

 the question in silence. 



Mr. Dalton states that the electro-chemical polarity of the atoms 

 makes no necessary part of the atomic theory, such as he maintains; 

 nor did I ever mean to convey any such idea to the reader For 

 my own part, in considering a corpuscular theory of chemistry, I 

 conceived that it should constitute the fundamental theory of the 

 science ; and instead of being occupied with a part of the pheno- 

 mena, ought to embrace the whole. But when we treat of atoms 

 in a chemical theory, we ought to endeavour to find out the cause 

 of the affinity of these atoms. We ought to endeavour to combine 

 researches respecting the cause why atoms combine with researches 

 into the cause why they combine only in certain proportions. I do 

 not consider the conjectures which I hazarded on the electro-che- 

 mical polarity of the atoms as of much importance. I scarcely 

 consider them in any other light than as an ideal speculation deriving 

 some little probability from what we know of the chemical eflects 

 of electricity. Yet the ideas on the relation of atoms to their 

 electro-chemical properties, ought in my opinion to constitute an 

 essential part of the corpuscular theory of chemistry, such as I 

 view it ; because I consider it as the duty of a man of science to 

 endeavour to reach the first principle of the science, even though it 

 sliould be actually impossible to attain it. 



Mr. Dalton di>a|)proves the idea which I announced, tliat wc 

 ought not to suppose an atom composed of 2 A + 2 B, 2 A -f 3 B, 

 &c. He thinks that such coml)inatioiis take place, though but 

 seldom. He inclines even to the idea tl-.at olefiant gas may be 

 composed of two atoms of carbon to two of hydrogen, j)laccd in 

 the furu) of a rhombus, those of hydrogen being at the extremities 

 of the longest diameter. Is there a chemical fact which counte- 

 nances such an idea of the conMniction of the atoms of olcHaiit 



