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of o.ening up pyrites in a current of oxygen put forward
by J mnasch in the Journal fur Praktische Chimit, 1889 ,
was described by A. Sour in 1873 in the Zeitschrift fur
AnaL Chimie (xii., 32).

On the Coefficients of Refra(5tion of Saline
Solutions.— B. Walter finds that salts may be divided
into a number of groups which have different molecular
refra^ive powers. Within a group the refrad^ive power
of a solution depends only on the number of the saline
molecules present in the solution whether they belong to
one or more salts if the latter only are members of the
same group. There is also reference to two papers on
the same subjedi in the CompUs Rtndus,

The Volatility of Hydrochloric Acid.— R. B. War-
der.— From the Amtrican Chemical journal.

The Acceleration of Incineration in Platinum
Crucibles. — H. von Jtiptner (Chemiker Ziitung), — This
paper requites the accompanying figure.

The Production of a Vacuum in an Exsiccator. —
B. Franke (Chem» Industrie), — This paper also cannot be
made intelligible without the figure.

The Acceleration of Filtration.— R. A. Fessenden.
— From the Chemical News.

On Thermometer.— L. Cailletet.— From the Comptn
Rendus,

A Gas-Balance with a Compensator. — A. Siegert
and W. Durr.

A Dilatometer. — O. Kn5fler {Annalm der Physik).

Automatic Arrangement for Turning Off Gas
when the Flame Strikes Back {Chemiker Zeitung), —
Le Roy W. McCay.— If the flame strikes back it
burns a string, and the cock is closed by the release of a
spring.

Mercurial Air- Pump without a Cock.— F. Neesen
{Zeit.fur Instrumentenkunde), — No particulars are here
given.

A Simple Water Blast. — M. Borner (Zei(, Angew,
Chemie). — An improvement on that of Beutell.

Diffusion of Gases through Flexible Tubing.— F.
J. Smith.— From the Chemical News. I

The Introduction of Two Gas-tubes into Narrow- 1
necked Flasks.- O. Kleinstiick (Chemiker Zeitung),^ \
The author passes into a cotk, with a single perforation, 1
a tube with an escape-tube melted on at right angles, and
introduces another tube through the latter, '



Drying Apparatus for the Determination of Pate
in Cattle Foods which contain Drying Oils.— O.
Forster (Land, Versuchsstationen), — This paper requires
the three accompanying couples of figures.

The Use of Hydrofluoric Acid.— £. Hart.— From
the jfourn, of AnaL Chem.

The Use of Magnesium as a Reagent.— H. N.
Warren.— From the Chemical News.

Standardising a Silver Solution with Potassium
Chromate as Indicator.— H. Alt (Chem, ^W/.).— The
author uses barium chloride instead of hydrochloric acid.
The barium is then removed by the addition of zinc
sulphate.

Preparation of a Solution of a Ferric Salt of
Known Strength.— W. French.— From the Chemicai*
News.

The Methods for Obtaining Chlorine.— P. Klason
(Swenskkemisk Tidsskrifl and Chemiker Zeitung), — From
manganese acd hydrochloric acid, the best proportions, the
yield obtained is 75 — 80 per cent of the theoretical quan-
tity. From sodium chloride (ix parts), manganese per-
oxide (90 per cent), 5 parts, and sulphuric acid 14 parts
the yield is 90 parts. From manganese, hydrochloric and
sulphuric acids only 65 per cent. The preparation from
chloride of lime and hydrochloric acid was also examined.
It is not necessary to mould the chloride of lime, but this
method is inferior in point of economy to the use of
manganese.

Preparation and Preservation of Hydrogen Sul-
phides.— C. Kreuz (Oesterreieh Afotheker Vereins), — ^The
author fills vessels holding 150— aoo c.c. with distilled
water, which has been freed from air by boiling, cools
rapidly, and saturates with sulphuretted hydrogen from an
apparatus wnich has been in a^ion for some time. The
corks are cut off level and sealed with paraffin or sealing-
wax.

Preservation of Sulphuretted Hydrogen Water.—
A. J. Shilton.— From the Chemical News.

Separation of Barium, Strontium, and Calcium. —
A. Russmann.— (An Inaugural Dissertation).

Separation of Aluminium and Zirconium. — J,
Thomas Davis, jun.— From the American Chemical
yournaL

A Reagent for Aromatic Bodies with a Hydroxyl
Group at the Benzol Nucleus.— P. C. Plugge (Archiv,
der Pharmacie), — The author recommends mercuric or
mercurous nitrate containing nitrous acid. It produces a
red colouration with the substances in question. He finds
that benzol derivatives free from hydroxyl do not ^ive
this reaction, or not until they have been converted mto
hydroxyliferous derivatives.

Dete<5tion and Determination of Nitrogen in
Organic Bodies.— £. Donath (bdonatshefte fur Chemie),
— This paper has been noticed some time ago. Donath
maintains that on oxidising nitrogenous organic matter
with potassium permanganate in an alkaline solution the
nitrogen is converted into nitric or nitrous acid.

The Application of Kjeldahl's Method in Hygienic
Researches. — B. Proskauerand M. Ziilzer. — The authors
use a decomposition mixture of 800 c.c. concentrated
sulphuric acid, 200 c.c. fuming sulphuric acid, and 100
grms. phosphoric anhydride. From 0*5 — 1*5 grm. of the
sample are taken for analysis, and digested with 20 c.c.
of the acid mixture, with the addition of i grm. mercury
and o'5 grm. anhydrous copper sulphate, until the liquid
is nearly colourless. The ordinary subsequent oxidation
is by adding minute crystals oi permanganate. A solution
of Congo-red, i grm. per litre, is used an an indicator.

Detection of Paraffin in Bees'- Wax.— H. Hager
(Pharm. Central Halle), — The author's method depends
on the sublimation of paraffin. The process cannot be
made quantitative.



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202



Meetings for the Week.



rCBEMICALNBWt,

1 April 24* t89t.



Separation of Barium and Strontium. -» R.
FreBenius. — The author sums up the results of a pro-
longed investigation as follows : — i. Barium chromate is
not soluble in water containing acetic acid, if so much
ammonium chromate is present that the liquid contains
only alkaline acetate and bichromate. 2. Barium chro-
mate dried at no** is not anhydrou» (as formerly assumed),
but contains about 0*5 per cent of moisture. 3. Barium
chromate is not decomposed on gentle ignition, and if
adhering to a filter it may be weighed without loss by
cautiously incinerating the filter and gently igniting the
residue. 4. The determination of barium by precipita-
tion with ammonium chromate gives results which are
perfeAly satisfadory. 5. The complete separation of
barium from strontium by a single precipitation of the
former as a chromate is not successful under any circum-
stances. The most favourable results obtained in this
manner depend on the accidental compensation of errors
of a Confliding nature. 6. A complete separation of
barium and strontium, and an absolutely satisfadory
result in the determination of both bases can be obtained
only by a twice repeated precipitation of the barium in
an acetate solution with an excess of ammonium chro-
mate ; the strontium can then be (brown down first as
strontium carbonate, which is then purified by conversion
into the sulphate.

Band-Spedra in the Eledric Arc of Carbon.^H.
Kayser and C. Runge.^No particulars are given.



MEETIMGS FOR THE WEEK.

Monday, 37th.— Medical, 8.30.

Society of ArU, 8. ** The Decorative Treatment of

Natural Foliage,*' by Hugh Stannui, F.R.I.B.A.
TUBSDAY, 28tb.->Inslitnte of Civil Eogineere, 8.

^—~ Royal Medical aod CbirurgicaU 8.30.

Royal Institution, 3. *• Bafteria: their Nature and

Punaions." by Kdward E. Klein.
Wbdnbsoay, a9th.~Society of Artt, 8. " The lUe of Petroleum in

Prime Motors," by Prof. William Robinson.
Thubsday, 30th.— Royal, 4.30.

^— Royal Society Club, 6.30.

Royal Institution, 3. " Recent SpcAroscopic In-

vestigations," by Prof. Dewar, M.A., F.R.8.

Society of Arts, 4.30 *' The Perrier Irrigation

ProjeA, Madras Presidency," by Col. J. O.
Hasted. RE.
Fbxoay, May ist.—Royal Institution, 9. '* Hawks and Hawking," by
James Edmund Hartiog.

Royal Institution. 5. Annual Meeting.

- Geologists' Association, 8.

Quekstt, 8.

Satuboay, and.— Ro\'al Institution, 3. •* The Dynamo," by Prof.
Silvanus P. Thompson, D.Sc, B.A.



PATENTS.

Provisional ProteAion, from £2 2««

Lowest cost of complete English and Foreign on application.

Also, Designs and Trade Marks. Inventions financed.

WALLACE WEATHERDON, & CO.

Rboistbbbd Patbmt Agents,
57 & 58, Chancery Lane, and ix, Southampton Buildings, W.C
Efttablished 1849.

PATENTS, DESIGNS, & TRADE MARKS ACT,
1883 TO 1888.

NOTICE IS HEREBY GIVEN that
Hobace Koechlin, of Loerrach, in the German Empire, has
K plied for leave to amend the Specification of the Letters Patent
>. 4899 of i8fex, granted to JoHW Imray, for " Improvements in the
manufaAure of colouring-matters." , . , ^ ,„

Particulars of the proposed amendment were set forth in the Illus-
trated Official Journal (Patents) issued on the 15th April, 1891.

Any person may give notice (on Form G) at the Patent Office, 25,
Southampton Buildings, London, W.C., of opposition to the amend-
ment witnin one calendar month from the date of the said Journal.
(Signed) H. READER LACK,

Comptroller General.



WILLIAM F. CLAY,

CHEMICAL AND TECHNICAL BOOKSELLER,

Teviot Place, Edinburgh.

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for Great •j Enlarged Monthly Issue at former cost. [ X2a.p.ann.

Britain. ( Copies sent for IncpcAion on Application. ) poet free.



n^HE LONDON HOSPITAL MEDICAL

1 COLLEGE.

The SUMMER SESSION will COMMENCE on FRIDAY,
May ist.

The Hospital, which is the largest general hospital in tbe kiofdom,
contains nearly 8co beds, ail in constant use. There are wards for
accidents, surgical and medical cases, diseases of women and
children, aod ophthalmic cases. Special departments for diaeaaea of
the e\e, ear, throat, skin, and teeth.aod for cancer, tumours, diaeaftcs
of the bladder, piles, snd fistula. Number of in-patientt last year,
9806; out-patients, 130,1^8; sccidenU, 8847.

Surgicsl operations daily.

APPOINTMENTS. — Resident accoucheur, house physicaans,
house surgeons, &c. Forty of these appointments are made annually.
N umerous dressers^ clinical clerks, post-mortem clerks, aod matcmit j
assistants are appointed every three months. All appointments are
free. Holdera of re&ident appointments are also provided free board.
The New College Buildings are now complete, and afford more than
double tbe former accommodation.

SCHOLARSHIPS AND PRIZES.— Twenty Scholarshipa mod
Prizes are given annually. Students entering in May are eligible to
compete for the four Entrance Scholarships in September.

Luncheons or dinners, at moderate charges, can be obtained in tbe
Students' Club.

N.B.— Special arrangements have been msde to meet the reqnire-
ments of the Examining Board in England so as to enable atndeota
entering in May to pass Part I. (Chemistry and Chemical Physics)
and Part II. (Materia Medica and Pharmacy) of the first ezamioatioa
in July.

The London Hospital ia now in dircA communication with all
parts of the metropolis The Metropolitan, DistiiA, and other rail-
way s have stations within a minute's walk of the Hospital snd College.

For further ioformstion spply personally or by letter to—

Mile End, E. MUNRO SCOTT, Warden.



Mr. a. H. HOLDICH,

Analytical and Consulting Chemist,

Over 17 years with the Wigan Goal and Iron Company, Lim.



Dl ATI M A UTENSILS and SCRAP, aleo

rLA I I IN A Old quicksilver,

Purchased for Cash by —

DERBY & CO., 44, Clerkbnwbll Road, London, £.0.

N.B.—Platina and Quicksilver Sold,



Silicates of Soda and Potash in the stat oi
Soluble Glass, or in CONCENTRATED SOLUTIO of firat
qoahty, suited for the Manuf^Aure of Soap and other purposes,
supplied on best terms by W. GOSSAQE and Sons, Soap
Works, Widnes. Lancashire.

London Agents, COSTE and Co., 19 and 20, Water Lane, Tower
Street. E. ~ . who hold stock ready for delivery.



J



MERRY AND CO.,



ASSAYtRS AND ANALYTICAL CHEMlSiS*
SWANSEA.

LTOR SALE. — The Chemical Gazette.

*' Complete Set (unbound and uncut), 17 volumes; from Novem-
ber, 1842, to December, Z8S9.— Address, " Publisher,*' CH*iiiCAt
NawB Office Boy Court. Ludgate Hill, London, B.C.

FOR SALE ON HIRE PURCHASE.

MACHINERY OF EVEKYDESCRIPTION
supplied on deferred payments or for Cash. New and secood>
hsnd. "W rite for Circular. InsptA stock.— ROWLAND G. FOOT
and CO. 12, Great 8t. Thomas Apottle, Cannon Suect, LoDdoD,E.C



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C"«"^«^,Niw^^ Commercial ValuaHon of Cream of Tartar Substitutes*



203



THE CHEMICAL NEWS.



Vol. LXIII., No. 1640.



COMMERCIAL VALUATION OF CREAM OF

TARTAR SUBSTITUTES.

By CHARLES A. CATLIN, Piovideoce, R.L

Fbw questioni are more perplexing to the analyst than
the commercial valuation of cream of tartar substitutes,
and more especially of those containing acid phosphate
preparations.

The ordinary methods of titration with standard alkali,
either dire^ly or indiredly employed, fail to give the
proper data, even with the phenolphthalein indicator, as
may be readily shown on taking the sample and bicar-
bonate of soda in the proportions thus indicated and boil-
ing up together in water, when it will be found that the
teaAion is incomplete, a greater or less proportion of the
carbonic acid failing of evolution, the amount varying in
the same sample with the quantity of water employed,
the temperature to which the mixture is submitted, and
the length of time through which it endures.

Other things aside, the value of a baking acid is, of
course, in its power of evolving carbonic gas rrom alkaline
bicarbonate when in admixture therewith under the con-
ditions in which it performs its office in the bread making
Srocess ; and since, as we have seen varying conditions
ave decided in6uence upon such readion, it is apparent
that no method of valuation can have real utility that
does not take into account and, as far as possible, initiate
the aAual baking process in these essentials.

To inform myself more exactly, I made many careful
observations of the steps pursued by a cook of the best
homespun order, in preparation of baking-powder biscuit
dough and subsequent baking of the same. I found that
she was using about 504 grms. of flour (Haxall brand) for
the quart, as leavening for which two heaping teaspoon-
fuls of a popular brand of baking-powder, weighing
together about 17 grms., and for moistening, 386 grms.
of either milk or water, or about 23 c.c. of liquid for each
grm. of baking-powder employed.

The range of temperature and the length of exposure
thereto were noted as follows: — When the dough was
ready for baking, a thermometer was inserted so that the
bulb might be held as near as possible at the centre of the
biscnit or loaf» and the whole placed in the already-heated
oven by the cook in the usual manner, the range of the
temperature being observed through a peephole, and
record made thereof at stated times.

Averaging a series of accordant results thus obtained,
I found the oven at the outset to have a temperature of
about 380** F., and that the temperature of the interior of
the dough passed through the following range :—

AfUr I minute's exposure in the oven , . . . 95' F»

,» 3 M M i» .... 130^ ,1

», 4 If II II .. •• 150 ft

„ 5 »» *• •» •• .. 100 „

,1 7 II II II .... 205 „

„ 10 It II »i .... 205 „

„ 12 11 If II •• •• 210 ,1

„ 13 It II II .... 212 ,1

„ 15 II II 11 •• •. 212 ,1

,1 17 II i» »» •• •• 217 II

After thirteen minutes' exposure, the cook pronounced
the biscuit ** done," but for the sake of the experiment,
the heating was continued when, after fifteen minutes,
the crust had become far too brown to be palatable, while
at the end of seventeen, a^ual burning had well com-



menced. From the above it is apparent, then, that in the
adual baking process the temperature of the dough is
raised gradually, through a lapse of about thirteen
minutes, to a temperature of not more than 212** F., and
for a successful issue, this should not endure for mora
than one minute, if indeed it should be allowed to con-
tinue for that length of time.

Consideration of these conditions of the adlual baking
process has led me to adopt the following method for
determining the value of cream of tartar substitutes
generally, and more especially of those having so-called
acid phosphate as the adive agent :—

The first step is to determine the neutralising power of
the sample by titration with caustic alkali, using phenol-
phthalein as the indicator. To do this, weigh one grm.
into a 300 c.c. titrating flask, run in upon it 100 c.c. of
water, add i c.c. of phenolphthalein solution (i grm. in
250 c.c. equal parts alcohol and water), agitate a few
minutes to effed complete solution or dissemination of
the sample, and then titrate with normal caustic alkali to
light pink colouration. The amount of solution used to
effed this is noted, a further addition is made in excess,
and the whole is brought to a rapid boil and kept there
for a few minutes. If now the pink colour has faded out,
a further addition of alkali is nvide, and another moment's
boiling allowed, and so on till a permanent pink colour is
obtained, noting of course the alkali used. It is my custom
to make these additions a cubic centimetre at a time, and
in ^most cases I find the first excess of i c.c. sufficient.
While the solution is still hot, add in c.c. quantities
normal sulphuric acid, and then titrate back to light pink
with the normal alkali. If normal solutions are used, the
statement will then be :— Total alkali, less acid added,
equal neutralising power of i grm. of sample. From this
calculate equivalent bicarbonate of soda.

As there is found to be no definite ratio between the
neutralising capacity of these preparations and their gas
evolving power when in admixture with alkaline bicarbon-
ate under the conditions of the baking process, and since
this alone is the measure of their efficiency, their valuation
should depend upon their determination of this quality.
To arrive at this, weigh into a perfectly dry flask one grm.
of the sample and also the exadt equivalent of pure bicar-
bonate of soda as indicated by the titrating process.
Perfedlly bicarbonated soda is scarcely to be found, but it
may be obtained very nearly by precipitation from a strong
solution of pure mono carbonate supersaturated with car-
bonic acid, drying the salt with bibulous paper as far as
possible, then powdering, and finally drying over oil of
vitriol, under a bell glass, in the ordinary manner. Thus
prepared, it is hardly necessary to make allowance for the
slight trace of monocarbonate which seems to be all but
unavoidable. Its carbonic acid strength should be care-
fully determined, however, for accurate work. The flask,
fitted with the usual stoppered funnel and exit tube, into
which has been weighed the charge of sample and its
equivalent bicarbonate, is attached to a carbonic acid
absorption apparatus of any of the well known types.

Personally I much prefer the soda-lime tubes to the
potash bulb, but this is a matter of individual experience.
In the adual baking process, we found that 23 grms. of
water were employed for each grm. of baking-powder
used. A large part of this water must have been
pradically inert in bringing about reaAion between the
constituents of the powder, being absorbed by the flour.
Just what that loss of water would be we have not the
means of determining, but certainly not more than half
the water employed can be considered as exerting solvent
aAion upon the powder. I would therefore recommend
that not more than 20 c.c. be used for each grm. of acid
sample and its soda bicarbonate equivalent. A very
much larger amount would so alter the conditions of
reaction that unreliable results would be the consequence.
A very much smaller amount would be impraAicable to use.
In the flask, after attaching the absorption apparatus, in-
troduce therefore through the funnel tube 20 c.c. of water,



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204



Coloured Reactions of the Aromatic Amines.



I CnsMiCAL Kiws,
I May I, X891.



and disseminate the powder through it by careful
agitation of the whole. We have seen in our observation
of the baking of the biscuit, that in the matter of tempera-
ture, 212* F. is never exceeded within the dough in proper
manipulation, and that limit should never be allowed to
endure for more than one minute at the longest. As a
matter of fad, I believe that when the temperature
reaches 200** F., or even a much lower point, the dough
has attained such a consistency that further evolution of
gas is rather an injury than an advantage. However this
may be, it is certain that gas evolved beyond the limit of
a temperature of 212'' F., enduring for one minute, is of
no pradical value. The contents of the flask is therefore
gradually raised to the boiling-point, and as we have ob-
served in the baking process, maintained at that tempera-
ture not longer than one minute, then aspirate the flask
and note the increased weight of the absorption tubes,
which gives us then the amount of carbonic acid evolved
under the baking conditions, and is consequently the
corredt measure of strength of the sample for the purpose
for which it is designed. Knowing the carbonic acid con-
tents of the bicarbonate of soda used, the results obtained
as above may be readily checked by again attaching the
absorption tubes to the flask and running in through the
stoppered funnel a few c.c. of dilute sulphuric acid,
whereby the remaining carbonic acid will be evolved.
Aspirating the apparatus again, the total increase in
weight of the absorption tubes above the first weighing
should correspond with the calculated amount of carbonic
acid in the bicarbonate of soda used.

This last step suggests a more rapid method of
procedure :—

Find the neutralising power of the sample as before,
then into the flask of the carbonic acid apparatus weigh
one grm. and its eauivalent bicarbonate of soda, add the
20 c.c. of water, bring the whole to a boil, and keep it at
that temperature not longer than one minute, the flask
being detached from the absorption tubes meanwhile,
blow out the flask to remove all of the carbonic acid thus
evolved, then attach to the absorption apparatus and
determine the carbonic acid still remaining unevolved by
adding the dilute sulphuric acid, &c., as before. The
carbonic acid thus obtained, deduded from the total
calculated carbonic acid of the bicarbonate of soda em-
ployed, gives the gas-evolving power of the sample under
the conditions of the baking process.

For a convenient statement of results I would suggest
taking the carbonic acid equivalent of one grm. of pure
bitartrate of potassium, i,e , 0'2340 grm., and expressing
results in thousandths of that standard, obtained by re-
moving decimal point, adding three o to the amount of
carbonic acid carried to tenths m.grms., and dividing by
2340.— 7oMr;ifl/ 0/ Analytical Chemistry, iv., Part 4.



ON U. GAYON'S ALDEHYD REACTION.
By H. BORNTRAGER.

For the detedion of aldehyd with spirit U. Gayon
{Comptis Rendus) proposes a solution of maeenta which
has oeen previously decolourised by the addition of a
little hydrochloric acid and much sodium bisulphite. The
writer has used this readion for about two years, and
concludes from his experience that it is fundamentally
useless for the purpose in question, from the following
reasons : —

The solution is in a short time turned red again by
atmospheric air, in consequence of the presence of ozone,
hydrogen peroxide, nitrous acid, &c. (possibly by oxygen
alone) ; a phenomenon which may be observed on the
stopper of the bottle, since the bisulphite (the decolour-
ising agent) is converted into bisulphate when the colour of



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