Scientific American Supplement, No. 623, December 10, 1887 eBook

This eBook from the Gutenberg Project consists of approximately 122 pages of information about Scientific American Supplement, No. 623, December 10, 1887.

Scientific American Supplement, No. 623, December 10, 1887 eBook

This eBook from the Gutenberg Project consists of approximately 122 pages of information about Scientific American Supplement, No. 623, December 10, 1887.

  [Footnote 38:  Different forms of flowers on plants of the same
  species.  Introduction.]

  [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:  Ranunculaceae, Berberidaceae, Carophyllaceae, Polygalaceae, Bromeliaceae, Liliaceae, Smilaceae, Yuccas, Amaryllideae, Leguminosae, Primulaceae, Rosaceae, Sapindaceae, Sapotaceae]

  [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.

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Scientific American Supplement, No. 623, December 10, 1887 from Project Gutenberg. Public domain.