64 
ME. J. J. WATERSTON ON THE PHYSICS OF MEDIA COMPOSED OF 
Dr. Turner defines the peroxide of hydrogen, 100 volumes, to consist of 100 oxygen 
-p 100 hydrogen, whereas, since the vapour has never been weighed, it is just as 
likely to consist of 50 volumes of each; both gases unite with others in several 
instances in half volumes, so that, until the experiment has been made, all that can 
be stated is that 17 by weight of the peroxide consists of 1 hydrogen + 16 oxygen. 
As soon as we have ascertained the space occupied by the 17 of the peroxide in 
comparison to the 1 of the hydrogen we can state its composition by volume, but 
it is surely confusing the subject of volumes altogether to infer this from the 
combining weights alone. 
In this Table the specific gravity of a simple gas in terms of hydrogen unity is 
taken as the value of its symbol (Col. 3, Part I.), and wdien this is inserted in 
parentheses (as from Nos. 10 to 20), it represents the value that has been assigned to 
the symbolical letter of the element in the compounds that follow, and indicates that 
it has not as yet been weighed in the simple vapour. 
Thus the value of C is 12, of F 19, &c., throughout the Table wherever these letters 
occur, and at the side these numbers are taken as unity in denoting the several 
proportions with which they have been found to combine in a single volume of 
compound gases and vapours. Opposite hydrogen, for example, we see numbers from 
up to 16, which informs us that from a volume up to 16 volumes of this gas 
enters into one volume of its compounds, and the same with regard to the others. 
These indicate in some degree the molecular capabilities of the element. They are 
ratios that have been taken from vapours that have actually been weighed as v 7 ell as 
analysed. A large proportion of them are of recent determination, and the original 
details of the experiments by Dumas, Mitscherlich, Regnault, Laurent, and Bjneau 
are to be found for the most part in the ‘ Anuales de Chimie ’; the reference to the 
volume and page of this invaluable work is given in parentheses after the name of the 
vapour, and the letter (m) is a reference to Mitscherlich’s ‘ Chemistry,’ where 
several specific gravities of vapour are given that are not to be found elsewhere. 
In the table of binary compounds a column is occujDied with the chemical 
constitution of a single volume of each in terms of volumes of its elementary 
components. Thus, nitric acid is represented by 0 2 JSi, which means that one volume 
of nitric acid vapour is composed of 2^ volumes oxygen united to one volume nitrogen, 
and where a volume has not been weighed, although its constitution by weight is 
known, the symbol is within parentheses, thus [ ]. 
In the ternary and organic compounds the simple constitution of a volume is given 
in the first place, as with the binary, and in the next column the most probable 
arrangement of the constituents, when there is any ground for making a hypothesis. 
Thus we have oxalic ether, No. 114, evidently composed of one volume oxalic acid 
and one volume of sulphuric ether condensed into one volume. This also allows us 
to infer wfith great probability the specific gravity of oxalic acid vapour. The next is 
nitrous ether, No. 115, which is quite a similar compound in the liquid form, but it 
