230 Phosphate of Alumine. 
produce nothing similar on the rosacic acid. Upon tie whole, 
M. Vogel concludes, with the exception of the circumstance of 
colour, and of the action of the sulphurous and sulphuric acids, 
that the rosacic: acid does not differ essentially from the uric 
acid; and nature, in changing the one into the other, makes no 
great effort.” 
PHOSPHATE OF ALUMINE. 
M. Vauquelin has published in the Annales de Chimie the 
following brief note on the phosphate of alumine:—‘* The 
method hitherto regarded as the best for separating the phos- 
phorie acid from iron, with which it is frequently mixed in the 
ores, consists in fusing the latter with potash, &c.; but if there 
is at the same time alumine in these ores, it is also dissolved in 
the alkali, and is found united to the phosphoric acid when we 
precipitate the latter, and increases the quantity of it. This 
alumine might make us believe in the presence of the phos- 
phoric acid, even when it does not exist, if we do not examine 
the precipitate with attention. 
‘* If the alumine exists with the phosphoric acid in an ore of 
iron, it is evident that these two bodies will be dissolved in the 
potash, will be precipitated from it when we saturate the alkali 
precisely by an acid, and will be redissolved together by an ex~ 
cess of acid. If we add lime water in order to precipitate the 
phosphoric acid, the alumine will be also precipitated; but if we 
treat the precipitate when still moist by a solution of potash, it 
will not be completely dissolved; and this will be the proof of the 
existence of the phosphoric acid : otherwise the solution would 
take place completely. 
‘*¢ This method appears to me the most certain, not only for 
ascertaining the presence of the phosphoric acid in iron ores, 
but also for estimating the quantity of it. In fact, we cannot 
analyse the phosphate of alumine either by the alkalies or the car- 
bonates: the former dissolve the entire combination, the others 
dissolve it in part; in such a way, however, that there is a greater 
quantity of phosphoric acid in the part dissolved than in that 
which is not, | ascertained this in the following way: I boiled 
a certain quantity of phosphate of alumine with a solution of 
carbonate of potash. I filtered the liquor in order to separate it 
from the undissolved portion, and | saturated with acetic acid 
the excess of the carbonate of potash : there was formed a pre- 
cipitate, which was phosphate of alumine. I afterwards put an 
excess of acid in the liquor, and [ assured myself that in this 
state it was not precipitated by ammonia; a proof that it did 
not contain any more phosphate of alumine: but it had been 
precipitated by lime water ; which proves that the alkali had di- 
vided 
