PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 429 



entering into combination, and forming steam, which is condensed 

 to two vohimes, or to two-thirds of the original bulk of these 

 gases in a separate state. Below 100° C. the steam is condensed 

 to nearly one-seventeenth hundredth of its volume, forming water. 

 As one cubic foot contains 1728 cubic inches, we may say that 

 two cubic feet of hydrogen and one cubic foot of oxygen combine 

 and form two cubic feet of steam, which may be condensed to 

 about two cubic inches of water. 



Fig. 8 represents three volumes of hj-drogen combining with 

 one of nitroofen, and formino^ two volumes of ammouiacal gas or 

 ammonia. Thus four volumes are condensed to two, the resulting 

 product being one-half of the bulk of the uncombined gases. To 

 express this chemical union of atoms it would be most proper to 

 say three atoms of hydrogen and one atom of nitrogen combine 

 and form an atomoid of ammonia. 



By using portions of the principal diagram on a much reduced 

 scale, many of the most important chemical combinations of the 

 non-metallic elements may be represented, and to each may be 

 added the name designating its ultimate constituents, according to 

 the new chemical nomenclature.* 



Fluorine, chlorine, bromine, and iodine, forming the family of 



halogens, are represented by figure C^ ^' One atom of fluorine 



being af; one of chlorine, ad; one of bromine, ab; one of iodine, 

 av; one of hydrogen, al; and the prefix g denoting the gaseous 

 state, I designate the acids formed by the combination of the 

 halogens severally with hydrogen, as follow: 



Hydrofluoric acid, HF, /\. alaf, at 16° (/alaf. 



Hydrochloric acid gas, HCl, l/\ galad. 

 Hydrobromic acid gas, HBr, /V^ galab. 



Hydriodic acid gas, HI, 



galav. 



Carbon combines in such a variety of proportions with hydro- 

 gen, nitrogen and oxygen, and in many instances assuming with 



* Transactions of American Institute for 1865-6, pp. 673-692. 



