478 
' The inferences drawn from these in- 
teresting and important facts are as fol- 
low: wa ‘ 
That calculi formed in the kineys, and 
immediately voided, are almost always 
composed of uric acid, and that the 
phosphates are very frequent ingredients 
i calculi of the bladder. They are uni- 
formly deposited upon extraneous sub- 
stances introduced into the bladder, but 
never form small kidney calculi.- In 
what is commonly called a fit of the gra- 
vel, asmall uric calculus is formed in 
the kidney, and passes along the ureter 
into the bladder. For, some time after 
a stone has passed from the kidney, the 
urine is generally unusually loaded with 
uric acid, and deposits that substance 
upon the nucleus now in the bladder. 
After this, the subsequent additions to the 
calculus consist principally of the phos- 
phates. 
Where the disposition to form uric 
acid in the kidneys is very great and per- 
manent, the calculus found in the blad- 
der is principally composed of uric acid ; 
but where this disposition 1s weak, the 
nucleus only is uric acid, and the bulk of 
the stone is composed of the phosphates. 
When the increased secretion of uric 
acid returns at intervals, the calculus is 
composed of alternate layers of uric acid 
and the phosphates. There are besides 
these many variations in the formation 
of the calculi. 
In speaking of the solvents, Mr. 
Brande admits, that the internal exhibi- 
tion of the alkalies often prevents the 
formation of the uric acid, and of course 
an increase of a calculus in the bladder, 
-as far as the uric acid is concerned; but 
that its action will not proceed any far- 
ther; because from his experiments he 
finds there is at all times a quantity of 
~uncombined acid in the urine; and hence 
it follows, that, although the alkali may 
may arrive at the kidneys in its pure 
state, it will there unite with the un- 
combined acid, and be rendered incapa- 
ble of exerting any action upon the cal- 
culusin the bladder. Mr. B. also ob- 
serves, that whenever the urine-is de- 
prived ofa’ portion of the acid which is 
natural to it, the deposition of the triple 
phosphate and phosphate of lime more 
readiy takes place, which is effected 
hy the exhibition of the alkalies; and, 
therefore, though alkaline medicines 
often tend to diminish the quantity of 
uric acid, and thus prevent the addition 
of that substance in its pure state to a 
calcu!us in the bladder, they favour the 
deposition of the phosphates. 
Proceedings of Learned Societiese 
= = 
{June I, 
With regard to the exhibition of the 
acids,- particularly the muriatic acid, in 
order to dissolve the phosphates, Mr. B. 
admits, that; during the use of this acid, 
the phosphates are either diminished, or 
disappear altogether; and even the urine 
acquires sometimes an additional acidity, 
and therefore a solution of that part of 
the calculus, which consists of the phos- 
phates, may be expected ; but even then 
the nucleus of uric acid would remain, 
and thus a great deal of time would be 
lost without any permanent -advantage. 
He is also decidedly against the injection 
of these solvents into the bladder, at 
once, by means of mstruments; because 
in every case that has come under his 
observation, it has always aggravated the 
sufferings of the patient. He concludes, 
that as the nuclei of calculi originate in 
the kidnies, and that of these thegreater 
. number consist of uric acid; the good 
effects so frequently observed during the 
use of an alkali, arise not from any ac- 
tual solution of calculous matter, -but 
from the power which it possesses of di- 
minishing the secretion of urine acid, 
and thus preventing the enlargement of 
the calculus ; so that, while ofa very small 
form, it may be voided by the urethra. 
In a following number we shall give-an 
account of Mr. Home's observations on 
the same subject. 
NATIONAL INSTITUTE. 
Messrs. Gay Lusac and Thenard have 
given an account of the method which they 
adopted in decomposing the boracic acid, 
They put equal parts of potassium,and pure 
vitreous boracic acid, into a copper tube, 
to which & bent glass tube was fitted. 
The copper tube was placed in a small 
furnace, and the extremity of the glass 
tube plunged into a bason of quicksilver. 
As soon as the temperature was raised 
to 150° (Reaumur, we presume), the 
mixture became suddenly red, much heat 
was produced, the glass broken, and al- 
most the whole of the air in the appa- 
ratus was driven out with great force. 
Only atmospheric air was disengaged, 
and a few bubbles of hydrogen. Atl the 
potassium disappeared, although. it only 
decomposed a part of the acid. These 
substances were changed by their re- 
ciprocal action into an olive grey sub- 
stance, which is a compound of potash, 
and of the basis of boracic acid. The 
boracic radical was separated from it 
by washing it with hot or cold water. 
That which does not dissolve, is the ra~ 
dical itself, which possesses the following 
properties: this radical is greenish 
ic ‘brown ; 
