Licence: Public Domain Mark
Credit: The diseases of the stomach / by Dr. C.A. Ewald. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![[The only advantages whicli Boas's test has over that of Grlinz- burg are that it is much cheaper and more stable. It may be kept unchanged for a very long time.] \Td])fer's Test.—Topfer * has recently proposed a test for free HCl which is exceedingly delicate, and which has the additional ad- vantage that it may also be used in quantitative analyses for the vari- ous combinations of HCl (see page 47). His reagent is a one-haK- per-cent alcoholic solution of dimethylamidoazobenzol, which turns red even in the presence of ^l per mille (1 to 40,000) HCl. It may be used either in solution or as a test paper, the latter being less delicate than the former. It is used as follows: To a few cubic centimetres of filtered stomach contents in a test tube or beaker add one drop of the test solution; if free HCl is present it will turn red. The test papers are prepared by dipping strips of filter paper into the test solution ; on drying they turn yellow. On dipping the test paper into stomach contents with free HCl a red color appears. Topfer and Friedenwald claim that this reagent responds only to free HCl, and not to combined HCl or organic acids. It has been shown, however, by Strauss f and Einhorn,;}: that it also responds to moderately concentrated solutions of acid phosphates and solutions of lactic acid in the concentrations in which it occurs in the stom- ach. Einhorn believes that if lactic acid is shown to be absent by Uffelmann's test we have an excellent means of determining the amount of free HCl. For the use of this test for quantitative work, see page 48.] The Tests for Organic Acids,—i. e., lactic, acetic, and the true fatty acids, especially butyric acid—^must now be considered. I have already discussed the occurrence of lactic acid in the earliest stages of digestion. But it is pathological if it or other organic acids are found in such quantities that they may readily be detected by the ordinary tests. It is characteristic of these acids that they are deriv- atives of the substances which occur normally in the chyme— i. e., starches, sugars, fats, and proteids—and that they are produced * [Topfer. Zeitschr. fiir physiolog. Chemie, Bd. xix, Heft 1. Friedenwald. N. Y. Medical Record, April 6, 1895.—Ed.] f [Strauss. Deutsch. Arch, fiir klin. Med., Bd. Iv.—Ed.J X [Einhorn. N. Y. Medical Journal, May 9, 1896, p. 603.—Ed.]](https://iiif.wellcomecollection.org/image/b21223026_0054.jp2/full/800%2C/0/default.jpg)
