162 ATTRACTION, 



then the numerical relations would not be in the least disturbed, only 

 the numbers expressing them would be doubled, tripled or quadru- 

 pled, &ic. according as the unit was placed lower in the scale. For 

 instance, should we find a compound in which hydrogen exists in half 

 the weight that it does in water ; then the composition of water, (the 

 lowest known proportion of hydrogen being still unity,) would be ex- 

 pressed by 1 of hydrogen and 16 of oxygen, and in the same manner 

 all other numbers expressing combining ratios would be doubled. 



(qq-) The foundation of the doctrine of definite proportions is 

 therefore laid in the constitution of things, and the facts discovered by 

 analysis, have been confirmed by calculation. If discovery had pro- 

 ceeded no farther, the knowledge obtained would have been both 

 highly valuable and interesting, but it was reserved for Mr. Dalton,* 

 to discover the next law which, although built upon that which has 

 been already announced, is perhaps still more extraordinary. 



(RR.) IF TWO SUBSTANCES UNITE, IN SEVERAL DIFFERENT PRO- 

 PORTIONS, THE LOWEST COMPOUND WILL CONTAIN ONE, OR BOTH 

 PRINCIPLES IN THEIR SMALLEST COMBINING PROPORTION ; AND IN 

 THE HIGHER, THE PROPORTIONS WILL BE SUCH AS ARE PRODUCED 

 BY MULTIPLYING THE LOWEST BY SOME WHOLE NUMBER. 



In a word, the higher proportions are multiples of the lowest, by 

 a whole number, or, the difference will be expressed by a whole 

 number, and the lowest is generally a divisor of the higher without 

 a remainder. 



In compounds of A-fB, supposing the first compound to be of the 

 smallest proportions of each, and that A remains constant, then the 

 other compounds will be A+2B, or -f 3B, or -f 4B. 



" The following tablef will illustrate the subject. 



Water is composed of hydrogen 1. oxygen 



Deutoxide of hydrogen do. 1, do. 16 



Carbonic oxide, carbon 6, do. 8 



Carbonic acid, do. 6, do. 16 



Nitrous oxide, nitrogen 14, do. 8 



Nitric oxide, do. 14, do. 16 



Hyponitrous acid, do. 14, do. 



Nitrous acid, do. 14, do. 32 



Nitric acid, do. 14, do. 40" 



In the two first lines, the proportion of hydrogen is the same, while 

 in the second that of the oxygen is doubled ; in the third and fourth 

 lines, similar relations exist between carbon and oxygen, and in the 



* Of Manchester, England, who is still living. i Turner, 2d ed. p. 151. 



