6 
of Chemical Equivalents. 
than is sufficient to saturate it, the quantity combined is then 
an exact simple multiple of the former, thus exhibiting a new 
modification of the law of definite proportions, rather than any 
exception to it. 
The first instance in which the same body was supposed to 
unite with different doses of another, in such proportions that 
one of these doses is a simple multiple of the other, was noticed 
by Mr. Higgins, who conceived, rather than actually observed 
to occur, certain successive degrees of oxidation of azote, and 
represented the series of its combinations with oxygen to be 
* Azote 1 with 2 oxygen making nitrous gas. 
Azote 1 with 3 oxygen making red nitrous vapour. 
Azote 1 with 4 oxygen making yellow nitrous acid. 
Azote 1 with 5 oxygen making white nitric acid. 
He at the same time added his opinion, that such are the 
proportions in which these gases unite to each other by bulk, 
having before observed one instance of union by exactly double 
bulk in the formation of water by the combustion of hydrogen 
and oxygen, and expressed his persuasion that the number of 
particles in a given bulk of the different gases is the same, and 
that the number of particles in the compounds of azote and 
oxygen, are successively in the proportions above stated. 
But though Mr. Higgins, in the instance of the union of 
hydrogen with oxygen, anticipated the law of bulks observed 
by M. Gay Lussac, with respect to the union of gases, and 
in his conception of union by ultimate particles clearly pre- 
ceded Mr. Dalton in his atomic views of chemical combina- 
tion, he appears not-f to have taken much pains to ascertain 
* A comparative View of the phlogistic and antiphlogistic theories, 1789, p, 133, 
t In straw ‘Colon red nitrous acid, the proportion appears to be four to onej but 
