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LXXXVI. On the rule for obtaining the Atomic Volume of 

 Elementary Substances. Bj/ Benjamin Boughey, Esq. 



To the Editors of the Philosophical Magazine and Journal, 

 Gentlemen, 



I FIND it stated in several works on the subject, that by 

 dividing the atomic weight of any element by its specific 

 gravity, the result will be the relative volume of its ultimate 

 atom or its atomic volume. But let us examine whether this 

 rule in its present state is constructed on sound principles. 

 If we take for example the case of oxygen gas, its specific gra- 

 vity is (water rOOO) about 'OOlSt; now if we divide this by 8 

 (its atomic weight), the result will be 5970. Again, take the 

 same oxygen at the temperature of 32°, and also at 212°, and 

 let its specific gravity at these temperatures be treated as 

 before, and we obtain for the atomic volume at 32°, 5500, 

 and at 212^, 7700. From these results it would appear that 

 an atom of oxygen fills a space at 32° equal to 5500; at 60°, 

 5970; and at 212°, 7700. But the most generally-received 

 opinion of an atom is, that it is incapable of expansion or 

 contraction, and that when heated the atoms themselves do 

 not undergo expansion, but are only further separated from 

 each other. But how must we reconcile the results just 

 given with this opinion? It thus appears that the rule just 

 stated is fallacious in its present state, but it is quite evident 

 that the fault lies, not with the rule itself, but with the spe- 

 cific gravity. 



The question then arises, how are we to avoid these objec- 

 tions ? It may be stated that they may be avoided by taking 

 the specific gravities all at the same temperature ; but are all 

 bodies in the state at the same temperature ? Are not some 

 solid, some liquid, and others gaseous ? and are not even 

 these states very irregular in their degree? If the specific 

 gravity of all the elements were taken at 212°, or at 32°, 

 would that of all be lowered or raised in an equal degree ? 

 Most decidedly not. Can any reason be given why we should 

 take the specific gravities of bodies just as we find them in 

 nature ? What relation do they bear to each other in that 

 condition ? 



What I have to propose is, that instead of taking the 

 specific gravities of bodies all at the same temperature, it 

 should be taken with all in the same state; either all solid, 

 all liquid, or all gaseous ; all heated or cooled, as may be re- 

 quired to bring the atoms of all to the same repulsion and 

 distance. Either of these three states might be taken, but 

 the liquid appears to me to be most convenient ; of course 



