HISTOBY OF THE ATOMIC THEOliY. 235 



" The following general rules may be adopted as guides in 

 all our investigations respecting chemical synthesis. 



'^ Ist. When only one combination of two bodies can be 

 obtained, it must be presumed to be a binary one, unless some 

 cause appear to the contrary. 



" 2nd. When two combinations are observed, they must be 

 presumed to be a binary and ternary. 



"3rd. When three combinations are obtained, we may 

 expect one to be a binary, and the other two ternary. 



"4th. When four combinations are observed, we should 

 expect one binary, two ternary, and one quaternary, &c. 



"5th. A binary compound should always be specifically 

 heavier than the mere mixture of its two ingredients. 



"6th. A ternary compound should be specifically heavier 

 than the mixture of a binary and a simple, which would, 

 if combined, constitute it, &c. 



"7th. The above rules and observations equally apply 

 when two bodies such as C and D, D and E, &c., are 



combined." 



• ♦♦»♦*» 



" In the sequel the facts and experiments from which these 

 conclusions are derived will be detailed, as well as a great 

 variety of others, from which are inferred the constitution 

 and weight of the ultimate particles of the principal acids, the 

 alkalis, the earths, the metals, the metallic oxides and 

 sulphurets, the long train of neutral salts, and in short, all 

 the chemical compounds which have hitherto obtained a 

 tolerably good analysis. Several of the conclusions will be 

 supported by original experiments. 



" From the novelty as well as importance of the ideas 

 suggested in this chapter, it is deemed expedient to give 

 plates exhibiting the mode of combination in some of the 

 more simple cases. A specimen of these accompanies this 

 first part. The elements or atoms of such bodies as are 

 conceived at present to be simple, are denoted by a small 



