THE OLD AND THE NEW CHEMISTRY. 
25 
which had been unknown in the time of Wenzel. The fact of 
constant composition of compounds had been firmly established : 
careful analyses of series of compounds of the same element had 
shown that a number may be attached to each element express- 
ing the relative amount of that element which combines with 
other elements to form compounds. This number was called 
the equivalent of the element. 
Hydrogen and oxygen combined in the proportion of 1 to 
8 ; hydrogen and sulphur in the proportion of 1 to 16; 
hydrogen and nitrogen in the proportion of 1 to 4*66. Hence 
8 parts by weight of oxygen were equivalent, so far as the 
power of combining with hydrogen was concerned, to 1 6 parts 
of sulphur, and to 4*66 parts of nitrogen. 
Hence in the equivalent notation the compounds of hydrogen 
and oxygen, of hydrogen and sulphur, and of hydrogen and 
nitrogen would be represented by the formulse HO, HS, and 
HN, respectively ; and the equivalents of oxygen, sulphur, and 
nitrogen would be 8, 16, and 4*66 respectively. 
But oxygen and nitrogen form a series of well-marked com- 
pounds ; the proportion of oxygen to nitrogen in the compounds 
was found to be (1) 8 : 14, (2) 16 : 14, (3) 24 : 14, (4) 32 : 14, 
(5) 40 : 14. In no member of the series were there less than 14 
parts of nitrogen, the amount of oxygen being taken as 8. 
But the study of the three compounds HO, HS, and HN 
showed that 8 parts of oxygen were equivalent to 4*66 parts of 
nitrogen : hence it appeared that in the lowest member of the 
nitrogen and oxygen compounds there were 3 equivalents of 
nitrogen ; the formulse of the series would then be ON 3 , 0 2 N 3 , 
0 3 N 3 , 0 4 N 3 , and O s N 3 . 
But these formulse were not adopted. It was assumed that 
the true equivalent of nitrogen was 14, and that the formula 
of the compound of this element with hydrogen was H 3 N : 
hence the formulse of the compounds with oxygen became 
ON, 0 2 N, O s N, 0 4 N, and 0 5 N, respectively. 
From certain data the formula of phosphoric acid was deduced 
as P0 5 , that of sulphuric acid as S0 3 ; but the amount of the 
former acid, expressed by the- formula P0 5 was capable of 
neutralizing three times as much soda, or oxide of silver, as the 
amount of the latter acid expressed by the formula S0 3 : hence 
the true equivalent formula of phosphoric acid should have been 
written -J- P0 5 . 
The study of reactions frequently led to the adoption of 
several equivalents, for one and the same element : to carbon, 
for instance, the equivalents 3, 4, 6, 8, and 12 were given 
according to the compound or compounds from the composition 
of which the number was deduced. 
These and similar facts were felt to militate against the 
universal adoption of a notation based upon equivalents. 
