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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![reagents toward the latter whether the reaction will occur in the presence of a definite amount of albumen, etc.; or, in other words, whether enough free acid will be left over to give the reaction after all the compounds have been formed which the acid may enter into in such a mixture. Therefore, in making comparative tests with solutions of acids which exceed the sensitiveness of a reagent, the more delicate the reagent the greater is the amount of the above-named substances [albumen, etc.] which may be added without preventing the reac- tion ; the opposite result will be observed if we are working with solutions which still contain even a trace of acid to act upon the reagent. This enables us to understand the statement made, for ex- ample, by Seeman,* that a combination of equal parts of a i-per- cent peptone solution and a 0-2-per-cent HCl mixture will just give the methyl-violet reaction; while Krukenbergf claims that the phloroglucin reagent (see p. 38) will do the same when one part of a 4-per-cent peptone solution is added to two parts of the identical HCl mixture. It simply means that methyl-violet is about fom' times less sensitive than phloroglucin-vanillin. As early as 1880 I called attention to this,:{: and showed, espe- cially concerning the methyl-violet reaction, that it was delayed by the presence of even small quantities of blood, and that it was markedly enfeebled or even prevented by solutions of hydrochlorate of leucin and tyrosin as well as by albumen and peptone. The or- ganic acids which have been alluded to above as affecting the color solutions include lactic acid, acetic acid, and butyric acid; yet, in order to simulate the changes produced by HCl, much stronger solu- tions are requisite than are found in the stomach contents,* l^evertheless, the value of these dyes as reagents for HCl is less- * Seeman. Ueber das Vorhandensein freier Salzsaure im Magen. Zeitschr. fiir klin. Med., Bd. v, 1882. f Krukenberg. Ueber die diagnostische Bedeutung des Salzsaurenachweises bei Magenkrebs. Inaug. Dissert. Heidelberg, 1888. X Ewald. Ueber das angebliche Fehlen freier Salzsaure im Magensaft. Zeit* schr. fiir klin. Med., Bd. i, S. 623. * A number of other reagents for free HCl, like Mohr's, Reoch's, Kahler's, etc., have also been published, which I have described in former editions, but have now omitted because they have only a historical value. Mohr employed the reaction which occurs on the addition of free HCl to a 10 per cent solution of sulpho-](https://iiif.wellcomecollection.org/image/b21223026_0051.jp2/full/800%2C/0/default.jpg)
