34 On the Dalionian Theory of [July, 



repulsion, as Buscovich supposed, appears tu me incomprehen- 

 sible. They must, 1 think, be physical points, as minute as you 

 will, but still possessed of length, breadth, and thickness. This 

 opinion, I say, is generally received by philosophers; and I 

 cannot, for my part, conceive any other. It is taken for granted 

 as the foundation of the DaltonLn theory ; and, 1 presume, will 

 be readily admitted by every one without hesitation. 



2. In cases of the chemical union of one body with another, 

 the substances combined are dispersed every where through the 

 whole mass. Thus chalk is a compound of lime and carbonic 

 acid. Now how minute a portion soever of clulk we take, we 

 shall find it to contain both lime and carbonic acid. How 

 minute a portion soever of water we take, we shall find it to 

 contain both oxygen and hydrogen. How minute a portion 

 soever of saltpetre we examine, we shall find it to contain both 

 nitric acid and potash. Now this could not be the case unless 

 the atoms of the combining bodies united with each other. 

 This accordingly is the opinion universally entertained respecting 

 chemical combinations. It has been long generally admitted, 

 and does not therefore require any farther illustration. 



3. All chemical compounds contain the same constant pro- 

 portion of constituents with the most rigid accuracy, no variation 

 whatever ever taking place. Water is universally composed of 

 1 part of hydrogen and JT'5 parts of oxygen ; sulphuric acid, of 

 1 part of sulphur and 1'5 part of oxygen ; carbonic acid, of 1 

 part of carbon and 2 - 7 parts nearly of oxygen, by weight. This 

 permanency of chemical compounds is generally admitted. 

 Indeed, the whole science of chemistry is founded on it, and 

 depends upon it. "Even Bcrthollet, who contends for indefinite 

 proportions in the abstract, admits the incontrovertible fact that 

 the proportions of chemical combinations in general are perma- 

 nent. 



•J. This permanency of chemical compounds cannot be owing 

 to any thing else than to the union of a certain determinate 

 number of the atoms of one constituent with a certain determi- 

 nate number of the atoms of the other. Let us suppose water 

 the compound. Let the number of atoms of oxygen which 

 unite be x, and of hydrogen y, then an integrant particle of 

 water will in every case be x + y. 



5. Oxygen has the property of uniting with different bases in 

 various proportions, sometimes in two, sometimes in three, four, 

 or even six proportions with the same base. Thus with azote it 

 unites in four proportions, with carbon in two, with mercury in 

 two, and so on. Now if we represent the weight of base with 

 which the oxygen unites by a, and suppose all the different pro- 

 portions of oxygen to unite with this portion of base ; and if we 

 denote the first portion of oxygen by b j then, in general, the 



