64 Mb. Grifpin on the Statical Relations of the Gases. 



in atoms, expressed in symbols. The value of the symbols is in all 

 cases the same as is given bj Berzolius. 



The third column contains the atomic weights of the elements and 

 compounds named in the two preceding columns. The atomic 

 weights of the compounds are, of course, the sum of the atomic 

 weights of their elements. The numbers used are those of Berzelius. 



The fourth column shows the Atomic Measure of the gases. The 

 mode of expression made use of here is now. It consists in employ- 

 ing a vulgar fraction, the denominator of which represents the sum of 

 the atomic measures of the constituents of a gas, while the numerator 

 shows the number of resulting volumes. — This method of expressing 

 Atomic Measures seems to me to be much more exact and convenient 

 than the method followed by many writers, of using small square dia- 

 grams for that purpose. — The atomic measure of a gas represents its 

 combining proportion. It contains the number of volumes, the weight 

 of which make up its atomic weight, (of course, in reference to some 

 fixed standard). The atomic measure of a compound gas is not the 

 volume occupied by its constituents, but the volume produced after 

 combination. 



The fifth column shows the specific gravity of the different gases, 

 in reference to the specific gravity of oxygen gas taken as a standard ; 

 or it denotes the weight in grains of as much in bulk of each gas as 

 would fill a vessel capable of holding 90.695 grains of atmospheric air, 

 or 100.000 grains of oxygen gas. 



The sixth column shows the specific gravity of many of these gases, 

 in reference to another standard, namely, atmospheric air, taken equal 

 to 1.0000. Such gases only are enumerated in this column as have 

 actually been weighed, and the numbers quoted represent the result of 

 the weighings. The blanks show what gases have never been weighed. 



An examination of these two methods of indicating the specific 

 gravities of gases, and a comparison of the numbers with those that 

 indicate the atomic weights and atomic measures of the gases, show 

 that great advantages would result from a more general adoption, by 

 chemists, of the series of numbers contained in the fifth column. In 

 the early days of chemistry, when only a few gases were known, it 

 was natural to compare their densities with that of atmospheric air ; 

 but at present it would be much more convenient to take the density 

 of oxygen gas as our standard, more especially when the density of 

 this very gas forms, as it does in this Table, the basis of the system of 

 atomic weights. 



The particulars contained in columns 3, 4, and 5, are brought into 

 calculations with the help of the following proportions: — If, of the 

 atomic weight, the atomic measure, and the specific gravity of a gas, 

 we know two terms, it is easy to find the third : — 



Let a. m. = the atomic measure ; a. w. = the atomic weight ; and 

 sp. gr. =. the specific gravity, Then, 



