PRINCIPLES OF THINGS. 41 



am at a loss how else to characterize it : for it has been minutely ascertained 

 within the last ten or twelve years, by an almost infinite variety of accurate 

 and well-defined experiments by Higgens, Dalton, Gay Lussac, and Davy, 

 that the combinations and separations of all simple bodies are conducted in 

 a definite and invariable ratio of relative weight or measure ;* as that of one 

 part to one part, one part to two parts, one to three, or one to four ; and, con- 

 sequently, that every change in the compound thus produced, whether of ad- 

 dition or diminution, is a precise multiple or divisor of such ratio ; or, in other 

 words, that the different elementary bodies which enter into such compounds 

 can never unite or separate, never lay hold of or let go each other, in any 

 other proportions. 



Let us exemplify this remark by a familiar instance or two. It is now well 

 known to every one that the calxes, oxides, or, as they are often called, rusts, 

 of metals, consist of a certain portion of oxygen with a certain portion ofj 

 the metal, which is thus converted into a calx or oxide. It is also known in 

 the present day to most persons, that the greater number of metals are pos- 

 sessed of two or more kinds of oxides,' produced by a union of different 

 proportions of the oxygen and the metal, and often distinguishable even by 

 their colour; as minium or red lead, and ceruse or white lead, which are 

 equally oxides of the metal whose name they bear. Now, in whatever 

 proportion the oxygen unites with the metal to produce an oxide of one ? 

 kind, it invariably unites by a multiple or divisor of the same proportion 

 to produce every kind of oxide belonging to the same metal. Thus we 

 have discovered not less than four different oxides of antimony in different 

 parts of the world: the lowest or simplest of them contains 4 parts of oxy- 

 gen to 100 parts of metal; the next simplest contains 18 parts of oxygen to 

 100 parts of metal, which is four times 4.v ; the third oxide consists of 27 

 parts of oxygen to 100 parts of metal, which is six times 4^ ; and the fourth 

 oxide, 36 parts of oxygen to 100 parts of metal, which is eight times 4!. 

 So tin, which possesses three discovered oxides, has for its lowest the propor- 

 tion of 7 parts of oxygen to 100 parts of metal ; for its second oxide, 14 parts 

 of oxygen to 100 parts of metal, which is twice 7; and for its highest, 21 

 parts of oxygen to 100 parts of metal, which is three times 7. I have given 

 the proportions in round numbers ; but if I were to use the fractions that 

 belong to them, the comparative results would be precisely the same. Nor 

 can we possibly combine these substances in any other proportions, so as to 

 produce oxides ; for the corpuscles of which they consist will not lay hold 

 of or let go each other in any other ratios. It is possible that we may here- 

 after detect an oxide of antimony consisting of a less proportion of oxygen 

 than 4i ; but if we ever should, we are confident beforehand that such pro- 

 portion will be 24. It is also possible that we may meet with an oxide con- 

 taining more than 4i and less than 18 parts of the oxygen in 100 ; but if we 

 should do so, we can nearly anticipate that such proportion will be 9. And 

 hence, as these proportions, though constantly true to their respective series, 

 are constantly diversified in different substances, their radical figures or num- 

 bers may be employed, and now actually are employed, and that very gene- 

 rally, and in perfect coincidence with the system of the Pythagorists, as sy- 

 nonymes of the simple forms or substances whose progressive character they 

 describe. This curious coincidence of ancient and modern philosophy, for 

 at present I will call it nothing more, I cannot but regard as a very marvellous 

 fact ; and am not a little surprised that it should not hitherto have occurred, 

 as.it does not appear to have done, to the minds of any of those learned and 

 ingenious chemists who have chiefly been employed in applying and building 

 up the discovery. And it is not the least important part of this discovery, 

 that not only in the union or separation of simple substances, but in all well- 

 known and more complicated compounds, so far as the experimental series 

 has been carried, the elementary bodies which enter into them exhibit pro- 



* The only apparent exception I am aware of to this general principle is in the combination of the ele- 

 ments of M. Dulong's detonating substance, or azotane, as described by sir Humphry Davy, Phil. Trans. 

 ftr 1813, p. 250: and it is hence probable that we are not yet put into possession of the proper results. 



