-1859] 



WRITINGS OP JOSEPH HENRY. 



113 



combination of volumes to illustrate this subject. In tliis 

 the volume of nitrogen, N, is considered as unity, and that 

 of oxygen as half unity : 



Table showing the grouping of elements in various nitrogen compounds, and 

 the difference in quality, effected by combination, 



N 1 Gas, inodorous, sweet, inactive. . . [Nitrous oxide.] 



Gas, colorless, insoluble, oxidizing. . [Nitric oxide.] 



Liquid, acid, unstable [Hyponitrous acid.] 



Gas or liquid, colored, acid, soluble. [Nitrous aoid.] 

 -2J Liquid, acid, colorless, corrosive. . . . [Nitric acid.] 



Gas, alkaline [Ammonia.] 



Liquid, detonating [Chloride of Nitrogen.] 



Solid, detonating [Iodide of Nitrogen.] 



Gas, combustible, odorous, poisonous. . [Cyanogen] 



IT I I I 



One of the peculiarities of the chemical combination of 

 bodies is the neutralization, in a greater or less degree, of 

 their attractions. Thus sulphuric acid and quick-lime, 

 which have a powerful attraction for other substances, and 

 are therefore highly corrosive, when united form "plaster of 

 Paris," a neutral, inert substance. An analogous result takes 

 place when the north and south poles of two magnets of equal 

 power are brought into contact; if they are not of equal 

 power, a residual action will be left in one. In a similar 

 manner two electrified glass balls, the one plus and the 

 other minus, both when separate attract the surrounding 

 objects; but when brought into proximity, they rush into 

 contact, and neutralize one another's attraction. This fact 

 distinguishes chemical attraction from the attraction of gravi- 

 tation, in which there is no neutralization of this kind, and 

 refers the former to that condition of the setherial medium 

 called electric, in which it probably exists in strata of differ- 

 ent densities around each separate molecule. The facts in 



