By E. MOLISABI.
[Illustration]
The author, after criticising the various methods for estimating fat
in milk which have been proposed from time to time, agrees with Stokes
(_Analyst_, 1885, p. 48), Eustace Hill (_Analyst_, 1891, p. 67), and
Bondzynsky (_Landwirth Jahrb. der Schweiz_, 1889), that the method of
Werner Schmid is the simplest, most rapid, and convenient hitherto
introduced. The conditions tending to inaccuracy are: The employment
of ether containing alcohol; boiling the mixture of milk and acid too
long, when a caramel-like body is formed, soluble in ether; the
difficulty of reading off the volume of ether left in the tube, owing
to the gradations of the instrument being obscured by the flocculent
layer of casein; when only a portion of the ether is used, fat may be
left behind in the acid mixture, as shown by Allen (_Chem. Zeit._,
1891, p. 331). The author believes that by the invention of the simple
apparatus represented in the accompanying figure, he has rendered the
process both accurate and convenient. This consists of a flask B of
about 75 c.c. capacity, which has a glass tap fused on, with two
capillary tubes attached, the one passing upward, the other downward.
The neck of flask B is ground into the neck of flask A, which holds
about 90 c.c. Either of the flasks can be placed in communication with
the external air by the opening _a_. The ether must be previously
washed with one or two tenths of its volume of water, to remove traces
of alcohol. The operation is performed as follows: 10 c.c. of well
mixed milk are weighed in (or measured into) flask A, 10 c.c. of
hydrochloric acid added, and the mixture heated to boiling on an
asbestos sheet. The boiling must not exceed a minute and a half, the
fluid being shaken from time to time, and not allowed to become of a
deeper color than a dark brown [not black]. The flask is cooled, and
25 c.c. of ether added. The two flasks are connected as shown in the
figure, the tap closed, and the whole shaken for a few minutes, the
flask being vented two or three times by the opening _a_. The
apparatus is now inverted, allowed to stand five or six minutes, the
tap turned, and the dark acid liquid drawn off into flask B. By a
little shaking of the ether the whole of the acid liquid may be easily
got into the lower flask. The apparatus is again inverted, then
separated, 10 c.c. of ether are introduced into the flask B, the tap
closed, and the fluids well shaken. When the ether layer is distinct,
the acid liquor is run off, and the ether solution transferred to A.
The whole of the ether solution is washed in the apparatus two or
three times with a little water, the flask A removed to the water
bath, the ether driven off, the last traces of ether and water being
removed by placing the flask in a drying oven heated from 107 to 110°
C., where it must remain at least twenty minutes. The usual cooling in
the exsiccator and weighing concludes the operation. Examples are
given showing its concordance with the Adams and other recognized
processes. Sour milk, which must be weighed in the flask, can be
conveniently analyzed; also cream, using 5 grammes cream and 10 c.c.
hydrochloric acid. (_Berichte Deutsch. Chem. Gesell._, 24, p.
2204).--_The Analyst._
* * * * *
AMERICAN ASSOCIATION--NINTH ANNUAL REPORT OF THE COMMITTEE ON INDEXING
CHEMICAL LITERATURE.[1]
[Footnote 1: From advance proof sheets of the Proceedings of the
American Association for the Advancement of Science; Washington
meeting, 1891.]
The Committee on Indexing Chemical Literature respectfully presents to
the Chemical Section its ninth annual report.
Since our last meeting the following bibliographies have been printed:
1. A Bibliography of Geometrical Isomerism. Accompanying an address on
this subject to the Chemical Section of the American Association for
the Advancement of Science at Indianapolis, August, 1890, by Professor
Robert B. Warder, Vice President. Proceedings A.A.A.S., vol. xxxix.
Salem, 1890. 8vo.
2. A Bibliography of the Chemical Influence of Light, by Alfred
Tuckerman. Smithsonian Miscellaneous Collections No. 785. Washington,
D.C., 1891. Pp. 22. 8vo.
3. A Bibliography of Analytical Chemistry for the year 1890, by H.
Carrington Bolton. J. Anal. Appl. Chem., v., No. 3. March, 1891.
We chronicle the publication of the following important bibliography:
4. A Guide to the Literature of Sugar. A book of reference for
chemists, botanists, librarians, manufacturers and planters, with
comprehensive subject index. By H. Ling Roth. London: Kegan Paul,
Trench, Trubner & Co. Limited. 1890. 8vo. Pp xvi-159.
This work contains more than 1,200 titles of books, pamphlets, and
papers relating to sugar. Many of the titles are supplemented with
brief abstracts. The alphabetical author catalogue is followed by a
chronological table and an analytical subject index. The compilation
extends to the beginning of the year 1885, and the author promises a
supplement and possibly an annual guide.
The ambitious work is useful but very incomplete. It does not include
glucose. The author gives a list of fifteen periodicals devoted to
sugar, and omits exactly fifteen more recorded in Bolton's _Catalogue
of Scientific and Technical Periodicals_ (1665-1882). Angelo Sala's
_Saccharologia_ is not named, though mentioned in Roscoe and
Schorlemmer and elsewhere.
Notwithstanding some blemishes, this work is indispensable to chemists
desirous of becoming familiar with the literature of sugar. It is to
be hoped that a second edition brought down to date may be issued by
the author.
5. A Bibliography of Ptomaines accompanies Professor Victor C.
Vaughan's work, Ptomaines and Leucomaines. Philadelphia, 1888. (Pages
296-814.) 8vo.
Chemists will hail with pleasure the announcement that a new
dictionary of solubilities is in progress by a competent hand.
Professor Arthur M. Comey, of Tufts College, College Hill, Mass.,
writes that the work he has undertaken will be as complete as
possible. "The very old matter which forms so large a part of Storer's
Dictionary will be referred to, and in important cases fully given.
Abbreviations will be freely used and formulæ will be given instead of
the chemical names of substances, in the body of the book. This is
found to be absolutely necessary in order to bring the work into a
convenient size for use ..., The arrangement will be strictly
alphabetical. References to original papers will be given in all cases
..."
Professor Comey estimates his work will contain over
70,000 entries, and will make a volume of 1,500-1,700 pages.
The following letter from Mr. Howard L. Prince, Librarian of the
United States Patent Office, explains itself: