Chemistry and Physics, 113 
With this. therefore the test solution was prepared, of such a strength, 
that each division, by measure in es ordinary alkalimeter tube, should 
be equivalent to the one-tenth or one-fourth of a grain of pure tannin, 
in water, or if necessary the astringent matter extracted by boiling, 
and the clear liquid precipitated by. the test solution: until no further 
deposit occurred.. 
was necessary in the course of this bei to test at iiervale a 
portion of the solution under examination, to ascertain the progress of 
the trial; and this, from the nature of a precipitate, was attended at 
first with some little difficulty : paper filters were inadmissible from the 
quantity of the solution they would absorb, and thus introduce a source’ 
of extensive error; subsidence rendered the operation very tedious. 
The pea. I have 6 adopted i is as follows :—a piece of glass tubing, about 
and this has a small‘piece of wet sponge loosely introduced 
ower extremity, and when it is wished to abstract a part of the 
ul ler investigation for a separate testing, this is immersed a few 
conds in gi partially precipitated solution; the clear liquid then 
filters by ascent through the sponge into the tube anes is to be decanted 
from its other extremity into a test glass; i if 0 siding a drop of the 
gelatin solution to this a fresh gnomes is mula, e whole is re- 
turned to the or riginal biti and the process procee sit in, and so on, 
until the operation is perfected ; 3 this rethicd ef operating is facilitated 
_by'co conducting the examination in a deep glass. After a few trials the 
‘manipulation will be found extremely easy, and in this way ie 
ble ac aed =e bea arrived a 
3. On the ieee ure Sulphuric Acid ; by Ava. A. Haves, 
‘of such te neces as were y iiearls ae in the hands of accurate 
oP isi . 
‘sumption, t the Soe is ae to this ¢ 
ithout entering into scientific details, I shall describe an economi- 
ess which | have carefully studied a by which the pure acid, 
ny laboratory, has long been obtai 
manu nufactories of sulphuric ea the weaker acid from. the 
is concentrated in lead pans, usually to the density of 
ferred without cooling to the platinum alembies for fur- 
9 commences with the hot acid, and it may be sup- 
posed to contain sulphurous acid, hydrochloric acid, hyponitrie acid, 
‘arseno us acid, oxyds of iron. and lead, ‘ney tn lime, soda. and epee 
matter, although the acid obtained of Sicily sul- 
phur, is rarely oye —. Ok additig pe aye t acid sufficient / 
© Ritrate of potash, a, to destroy the organic matter, the bro 
