ELECTROLYSIS OF SECONDARY COMPOUNDS. 
5 
nitrate of silver. There could be no doubt therefore that tritoxyphosphion (or the 
radicle of the tritohydrate of phosphoric acid) had travelled to the zincode. The 
experiment was more than once repeated with unvarying results. 
(i b .) A solution of tribasic phosphate of soda (3NaO, P 2 0 5 ) (sub-phosphate) was 
substituted in the same arrangement for the rhombic phosphate, and, after the action 
of the battery, on neutralizing the liquid in the zincode cell, a similar copious yellow 
precipitate was obtained from nitrate of silver. 
(c.) To complete the series of tribasic phosphates in which different bases are sub- 
stituted for each other, a solution of the phosphate of soda, ammonia and water 
/ NaO ] \ 
( NH 4 0 P 2 0 5 1 (microcosmic salt), was subjected in the same manner to elect ro- 
\ HO / 
lysis, the zincode cell being charged with solution of soda ; the solution in the zincode 
cell became acid to the test of litmus, and produced an abundant yellow precipitate 
in solution of nitrate of silver; proving that it was the tribasic acid which had tra- 
velled as before. 
(d.) A similar arrangement was made with a solution of dibasic phosphate (pyro- 
phosphate) of soda (2NaO, P 2 0 5 ). Hydrogen and oxygen in equivalent proportions 
were respectively given out at the platinode and zincode, and the process was carried 
on to the same extent as before. The solution at the zincode after electrolysis was 
neutralized by nitric acid. When tested with solution of nitrate of silver, a copious 
white precipitate was formed, indicating that in this case deutoxyphosphion (or the 
radicle of the deuto-hydrate of phosphoric acid) had been transferred to the zincode. 
(e.) A solution of monobasic phosphate (NaO, P 2 0 5 ) (metaphosphate) was sub- 
jected to electrolysis under the same circumstances. The solution in the zincode cell 
was now found to be strongly acid instead of alkaline ; when added to a solution of 
albumen it immediately coagulated it ; and with nitrate of silver and nitrate of baryta 
it produced the characteristic gelatinous white precipitates, which are distinctive of 
the monobasic phosphates of those bases. 
It was thus fully established by these experiments, and confirmed by their repe- 
tition, that the three hydrates of the phosphoric acid constitute three essentially 
distinct acids, which may be expressed as follows : — 
H +P 2 0 6 proto-hydrate, 
H 2 -fP 2 0 7 deuto-hydrate, 
Hg-l^Og trito-hydrate, 
and that when disengaged from their corresponding saline compounds by the power 
of the voltaic current, they travel as three distinct oxyphosphions in the circuit. This 
view, which cannot be doubted as arising from the properties of the acids so disen- 
gaged, derives confirmation from the observation that the quantity of acid transferred 
from the monobasic phosphate of soda was so much greater for the same amount 
of hydrogen disengaged, than from the dibasic and tribasic salts of the same base. 
