448 » On definite Proportions. 
only with its water, without suffering a particle of the acid 
to escape. The salt, thus dried, left after ignition 90°3 
percent. of oxide ; and in this process only nitrous vapours 
and oxygen were ‘disengaged, without an atom of liquid 
acid. These 90*3 parts Pak protoxide of lead contained 
6°457 of oxygen. And if we consider the nitric acid as 
consisting of ammonium and 87°88 per cent. of oxygen, 
the 9-7 parts contain 8°524 of oxygen, which is much less 
than twice the oxygen of the base: but if we consider the 
nitric acid as consisting of 30°5 parts of mitrogen and 69°5 
of oxygen, 9°7 parts of nitric acid contain 6°74,0f oxygen ; 
that is, neglecting the small difference of °317, which may 
easily have arisen from an error of observation, a quantity 
of oxygen equal to that of the base. 
This result appeared to be the more striking, as it seemed 
to contradict my earher ideas respecting the composition of 
the nitric acid; for L had not here to do with a double sub- 
salt of Jead : I had indeed been long acquainted with such a 
subacetate, and I particularly sought for ityin this case; 
having observed that if one boils the acetate of the prot- 
oxide of lead with more of the protoxide, one obtains a 
combination which does not crystallize, which acts on ve- 
getable colours like an alkali, and dries with heat into a 
mass of a gummy appearance. If this combination is di- 
gested with still more of the protoxide, the protoxide ex- 
pands and becomes white, the solution loses more and 
more of the lead that it contains, and retains at last an 
astringent taste, without sweetness. The white precipitate 
thus formed dissolves in boiling water, and shoots trom it 
into feathery crystals with a silky gloss. I have not yet 
gone so far as to be able to make out with certainty _ the 
composition of this salt ; but I have found that it contains 
much more metal than the salt with the appearance of an 
extract, and can be converted into it again by the addition 
of acetic acid. These two degrees of the subsalts may be 
termed subsalis and subsubsalts. 
I by no means expected, from the general law of the 
composition of salts which I have developed, that it would 
be necessary here to consider the nitric acid as composed 
of nitrogen and oxygen. Either (A) the observation must 
have been incorrect, or (B) the an sis of the neutral ni- 
trate of the protoxide of lead must have been inaccurate, 
or (C) there must have been some canse, with which I am 
sipsapniniea that nitrogen is affected in the nitric acid, 
when it is saturated with the greatest possible quantity of a 
base, as a simple substance, not contaming any oxygen, or 
(D) the 
