ATTRACTION. 



four last, while the proportion of nitrogen is constant, that of the 

 oxygen is double, triple, quadruple, and quintuple. 



This is the law that has usually been called the law of multiples, 

 or of multiple proportions, and there can be no doubt that it is true 

 to a very great extent, although, at present, we are prevented, by a 

 very few apparent exceptions, from regarding it as quite universal. 



Thus, hydrogen being 1, lead is represented by the number 104, 

 and manganese by 28, and each of these metals has three oxides, 

 which are found to contain respectively, 8, 12, and 16 of oxygen, 

 which is in the proportion of 1 1.5 and 2 ; so iron, whose equivalent 

 is 28 has, in its two oxides, 8 and 12 of oxygen, which also are in the 

 proportion of 1, and 1.5. This does not correspond with the doc- 

 trine of multiple proportions ; the difficulty would, however, be re- 

 moved, should an oxide of each of these metals be discovered, with 

 4 of oxygen, instead of 8 ; or possibly there may have been a mix- 

 ture of oxides, as of the protoxide and peroxide of lead, thus giving 

 origin to an apparent deutoxide, which may not really exist.* Should 

 these cases, however, prove in the end to be exceptions, they will 

 not invalidate the truth of the general doctrine. 



(ss.) The number representing any compound body is composed of 

 the sum of the numbers representing its parts. Thus in sulphate 

 of potash, whose equivalent is 88, sulphur 16, -f- 3 proportions of 

 oxygen 24=40, and potassa is composed of potassium 40, and 1 pro- 

 portion of oxygen, 8=48, which + 40=88; this will hold true of 

 the most complicated as well as of the most simple compounds. 



This truth is well illustrated by all the salts. 



(tt.) " The respective quantities of any number of alkaline, earthy, 

 and metallic bases required to saturate a given quantity of any acid, 

 are always in the same ratio to each other, to what acid soever they 

 may be applied "\ Soda 2 parts, and potassa three parts respective- 

 ly, these numbers always bearing the same relation to each other, 

 and to some unit, saturate every acid ; soda is represented by 32, 

 and potassa by 48, hydrogen being one, and 32 : 48 : : 2 : 3, as above, 

 and these numbers therefore constantly represent the combining 

 power of these two alkalies ; but the proportions of the different acids 

 which will combine with these, and with other bases, will of course 

 vary. 



(uu.) " The respective quantities of any number of acids requir- 

 ed to saturate a given quantity of any base, are always in the. 

 same ratio to each other, to what base soever they may be applied."^ 

 This is only the converse of the other proposition, the relative pro- 

 portions of any two acids that saturate a given base, will saturate any 



* Turner. t Prof. Olmsted, in Am, Jour, Vol. XII, p. 1. 



