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Page 42
[Footnote 39: Meehan: Proc. Acad. Nat. Sciences.]
[Footnote 40: H.C. De S. Abbott: Trans. Amer. Philos. Soc., 1886.]
[Footnote 41: For further facts confirming this theory, see
"Comparative Chemistry of Higher and Lower Plants." By H.C. De S.
Abbott. Amer. Naturalist, August, 1887.]
[Footnote 42: Different genera and species of the following:
Ranunculace�, Berberidace�, Carophyllace�, Polygalace�,
Bromeliace�, Liliace�, Smilace�, Yuccas, Amaryllide�, Leguminos�,
Primulace�, Rosace�, Sapindace�, Sapotace�]
[Footnote 43: Kobert: Chem Ztg.]
[Footnote 44: Compt. Rend., xciv, p. 1124.]
[Footnote 45: Bul. de la Soc. Chim.]
[Footnote 46: "Yucca angus." Trans. Am. Philos. Soc., Dec., 1885.]
[Footnote 47: Botanical Gazette, October, 1886.]
[Footnote 48: Borodin: Pharm. Jour. Trans., xvi, 369. Pax. Firemy:
Ann. Sci. Nat., xiii.]
[Footnote 49: H.C. De S. Abbott, Proc. Acad. Nat. Sciences, Nov.
30, 1886.]
* * * * *
NEW METHOD FOR THE QUANTITATIVE DETERMINATION OF STARCH.
A.V. ASBOTH.
The author maintains that unsatisfactory results are obtained in
determinations of starch when the method employed is based upon the
inversion of sugar, formed as an intermediate product, since maltose,
dextrose, and levulose are partly decomposed by boiling with dilute
acids. He proposes to replace the methods hitherto employed by one
which depends upon the formation of a barium salt of starch, to which
he assigns the formula BaO.C_{24}H_{40}O_{20}. This salt is sparingly
soluble in water and insoluble in dilute alcohol.
In making a determination a weighed quantity of starch is saccharified
with water, then mixed with an excess of normal baryta solution,
dilute alcohol added to make up to a certain volume, and, after the
precipitate has settled, the excess of baryta is titrated back with
acid.
[Illustration: Titrating apparatus]
The author also describes the apparatus he employs for storing and
titrating with baryta solution. The latter is contained in the bottle,
A, and the drying tube attached to the neck of the same is filled with
quicklime. The burette, B, which is in direct connection with the
bottle, may be filled with the solution by opening the stop cock, and
the small drying tube, _n_, is filled with dry KOH, thus preventing
the entrance of any CO_{2}. Numbers are appended which seem to testify
to the excellence of the method employed. The author finally gives a
detailed account of the entire analysis of various cereals.--_A.R. in
Jour. Soc. Chem. Indus._
* * * * *
SYNTHESIS OF THE ALKALOIDS.
In the note on the constitution of alkaloids in a recent issue, we
referred more especially to what we may term the less highly organized
bases. Most of our knowledge, as we now have it, regarding such
alkaloids as muscarine and choline has been acquired during the past
dozen years. This is not exactly the case with the higher groups of
alkaloids--the derivatives of pyridine and quinoline. It so happens
that the oldest alkaloids are in these groups. They have, almost
necessarily, been subjected to a longer period of attack, but the
extreme complexity of their molecules, and the infinite number of
differing parts or substances into which these molecules split up when
attacked, are the main cause of the small progress which has been made
in this department. All, however, yield one or more bodies or bases in
common, while each has its distinctive and peculiar decomposition
product. For example, cinchonine and quinine both afford the basic
quinoline under certain conditions, but on oxidation of cinchonine, an
acid--cinchoninic acid (C_{10}H_{7}NO_{2})--is the principal body
formed, while in the case of quinine, quininic acid (C_{10}H_{9}NO_{3})
is the principal product. The acquirement through experiment of such
knowledge as that is, however, so much gained. We find, indeed, that
obstacles are gradually being cleared away, and the actual synthetic
formation of such alkaloids as piperidine and coniine is a proof that
the chemist is on the right track in studying the decomposition
products, and building up from them, theoretically, bodies of similar
constitution. It is noteworthy that the synthesis of the alkaloids has
led to some of the most brilliant discoveries of the present day,
especially in the discovery of dye stuffs. Many of our quinine
substitutes, such as thalline, for example, are the result of
endeavors to make quinine artificially. If there is romance in
chemistry at all, it is to be found certainly in this branch of it,
which is generally considered the most uninteresting and unfathomable.
We may take piperidine and coniine as examples of the methods followed
in alkaloidal synthesis; these are pyridine bases. Pyridine has the
formula C_{5}H_{5}N, that is, it is benzene with CH replaced by N. The
relationship between these and piperidine is seen in the following
formul�:
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