330 Specific Gravities of Bodies. (Nov. 
Talle IT.—This table exhibits many striking instances of the near 
coincidence of theory and experiment. It will be seen that Gay- 
Lussac’s views are adopted, or rather indeed anticipated, as a good 
deal of this table was drawn up before | had an opportunity of seeing 
the latter part of that chemist’s memoir on iodine. ‘That table also 
exhibits one or two striking examples of the errors that have arisen 
from not clearly understanding the relation between the doctrine of 
volumes and of atoms. ‘Thus ammonia has been stated to be com- 
posed of one atom of azote and three of hydrogen, whereas it is 
evidently composed of one atom of azote and only 1°5 of hydrogen, 
which are condensed into two volumes, equal therefore to one atom; 
and this is the reason why this substance, like some others, appa- 
rently combine in double proportions. * 
Table I1I.—This table likewise exhibits some striking examples 
of the coincidence above noticed. Indeed, I had often observed 
the near approach to round numbers of many of the weights of the 
atoms, before I was led to investigate the subject. Dr. Thomson 
appears also to have made the same remark. It is also worthy of 
observation, that the three magnetic metals, as noticed by Dr. 
Thomson, have the same weight, which is exactly double that of 
azote. Substances in general of the same weight appear to combine 
readily, and somewhat resemble one another in their nature. 
On a general review of the tables, we may notice, 
1. That all the elementary numbers, hydrogen being considered 
as I, are divisible by 4, except carbon, azote, and barytium,-and 
these are divisible by 2, appearing therefore to indicate that they are 
modified by a higher number than that of unity or hydrogen. Is 
the other number 16, or oxygen? And are all substances com~ 
unded of these two elements ? 
2. That oxygen does not appear to enter into a compound in the 
ratio of two volumes or four atoms. 
3. That all the gases, after having been dried as much as pos- 
sible, still contain water, the quantity of which, supposing the 
present views are correct, may be ascertained with the greatest. 
aceuracy. 
Others might doubtless be mentioned ; but I submit the mattey 
for the present to the consideration of the chemical world. ; 
* See Gay-Lussac’s memoir on todine, Annals of Philosophy, vi. 189, 
