Cofurcar News, ) Contributions to Volumetric Analysis. 97
place under any circumstances. This burette, however,
T H E C H E M I C A L N E Ww S. is inconvenient to use because a constant watch must be
kept on its liquid contents if the outflow is to be regulated
with precision, and this is not an easy matter, as the attention
 of the operator is divided in observing both the
outflow and the effec of the test liquor on the solution in
the beaker glass. This defect is aggravated by the cir.
cumstance that, towards the end of the operation, when
the effe@ of every drop of test-liquor on the solution
under examination has to be watched with the closest
attention, the management of the burette becomes the
most difficult, on account of its greater deviation from a
vertical position.
Having suffered a great deal of inconvenience from this
defeq, I endeavoured to overcome it by several devices,
and was finally led to adopt an entirely new form of
burette, which I find more convenient than any other with
which I am acquainted, and which it is my business to
describe to you this evening

CONTRIBUTIONS TO VOLUMETRIC ANALYSIS.*
By P. CASAMAJOR.

FIRST PAPER.—ON A NEW PORTABLE BureTTE.
Tue necessity of estimating potassa and soda in their
commercial carbonates with accuracy and rapidity, gave
rise to volumetric analysis, and I believe that Descroizilles
was the first chemist who substituted the measuring of a
certain volume of acid of known strength for the slower
and more delicate operation of weighing.
To ascertain the exact volume of sulphuric acid required
to saturate a known weight of alkali, Descroizilles used a
graduated tube about 25 centimetres high, with a diameter
of 15 millimetres. This was provided with a very narrow
neck, whose upper portion was expanded and ‘provided
with a lip. On the shoulder, near the base of the narrow
neck, was a small opening, which, by being closed more
or less perfectly, by the application of a finger, allowed
the titrated acid to run out with more or less rapidity.
The word burette, applied to this instrument, was very
appropriate, as in French burette, as defined by Boiste,{
is a small flask with a narrow neck, and is a diminutive
of buire, which means a large flask. This word was
adopted afterwards by Gay-Lussac to designate his
graduated drop tube, and it has been applied to all instru.
ments designed to fulfil the same purpose, whatever be
the variety of their shapes.
In the burette of Gay-Lussac, which was the immediate
successor of the instrument of Descroizilles, the liquid is
poured out through a very narrow tube, which may have
been suggested by the narrow neck of the primitive flask,
This burette has the advantage over some other forms
now adopted that it is made entirely of glass, and is there.
fore able to hold any of the test liquors used in volu.
metric analysis, and also that its contents can only run
out when the instrument is in the hands of the operator.
I believe that it is generally preferred to other forms, and
that more of them are sold than of any other kind, Twa
other burettes are in general use, in both of which the
liquid drops directly from the bottom of the graduated
tube, its flow being regulated either by a glass cock, or by
a pinch cock acting on a flexible rubber tube. This latter
instrument is the invention of Dr. Frederick Mohr, and
we may say of it that, for solutions which have no a&ion
on india-rubber, no better burette could be desired.
In the investigations which I lately made on the
“ Estimation of Potassium as Acid Tartrate,” which I had
the honour of laying before you at our September meeting, 1
had repeatedly occasion to use a titrated solution of potassic
hydrate, which could not be held in Mohr's burette, on
account of the rubber tube, A burette with a glass cock,
which I used at first, was finally laid aside, as the normal
alkaline solution was continually leaking out around the
key of the cock. This key itself fitted very perfectly, but
it had to be slightly loosened: from its seat to allow it to
be turned with nicety, and the play left in this manner
was sufficient to let a portion of the contents leak out,
and, as the whole of this did not find its way to the
beaker glass, but some remained on the outside of the
burette, errors were committed which materially affected
my results. A burette of Gay-Lussac gave much more
satisfaory and concordant results, as no leakage took

The burette represented in Tig. 1 and Fig. 2, is a
cylindrical tube closed at the bottom. For the sake of
convenience and safety this tube is inserted in a stand or
foot, in the manner propgsad by Dr. Mohr for Gay-Lussac’s
burette. This foot is made of japanned tin, which is
setter in every way and more economical than wood.
The cylindrical portion of this tin stand is only partially
soldered on the flat part, to allow the portion left free to
act as a spring in holding the glass cylinder tightly.
The upper portion of the glass tube has the shape
shown in Fig. 1, to prevent the liquid from running out
when the tube is inclined, The same obje& is usually
accomplished by bending the upper portion at an obtuse
angle on the main stem ; but I have preferred the shape
shown in Fig. 1, as the burette is more easily filled
while standing vertically on its foot.
Immediately under the curved portion of the burette ig
1 beak, from which the liquid drops when the instrument

* Read before the American Chemical Society, November 7, 1876.
Communicated by the author,
t+ The definitions of Boiste are as follows i—Buire—s. f. flacon—
grand vase. Burette—s, I Urceolus—petite buire—vase 4 petit goulof
pour I'huile; pour eau et le vin 4 1a mess.