110 



WRITINGS OF JOSEPH HENRY. 



[1855- 



and the different kinds of matter the result of the different 

 forms in which the}^ are grouped, yet in the present state of 

 science there are sixty-one substances which are classed by 

 the chemist as simple bodies, and which must continue thus 

 to be classed until they shall be actually' de-composed into 

 two or more separate components. If these bodies consist of 

 elementary atoms, or of groups of atoms, always of the same 

 number and form, it will follow that all combinations of 

 them will take place in definite and fixed proportions. For 

 example, it is known that one part of hydrogen by weight 

 unites with eight parts of oxygen to form water, and this 

 liquid, whenever found, always contains the same propor- 

 tion of these ingredients. But there is another compound 

 of oxygen and hydrogen, of which the components are in 

 the ratio of one to sixteen, and this result is precisely that 

 which might have been anticipated from the theory of 

 atomic combination. In the first case, if the atom of hydro- 

 gen weigh one, (for instance, one millionth of a grain,) 

 and the atoms of oxygen eight, (eight millionths,) then 

 any amount of combination will have the same proportion. 

 The combinations then will be one to eight, one to sixteen, 

 and if another combination of oxygen and hydrogen exist, 

 it will be in the ratio of one to twenty-four. In the first 

 instance, it is one atom to one ; in the next, of one atom to 

 two; in the third case, it would be one atom to three. This 

 is also beautifully shown in the union of oxygen and nitro- 

 gen, of which there are five diflferent compounds, as exhibited 

 in the accompanying table. 



