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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![alkaline, the degree of alkalinity may be determined with a deci-nor- mal acid solution. ISTormal caustic soda solution contains 40 grm. to the litre, so that 1 c. c. deci-normal caustic soda solution is equivalent to 0-003646 grm. HCl or 0-009 grm. lactic acid. Phenol-phthalein, a derivative of benzol, is a buff-colored powder, freely soluble in alcohol, making a slightly opalescent solution, which remains color- less in acid or neutral solutions, but assumes a carmine color in alka- line solutions. The procedure is simple: a Mohr's burette * is filled with the deci-normal solution of caustic soda; 5 or 10 c. c. of the filtered stomach contents are poured into a small glass beaker, and one or two drops of the [one per cent] alcoholic solution of phenol-phthalein are added. The solution in the burette is very gradually added till the red color which appears in the contents of the beaker no longer disappears on shaking, but remains perma- nently. This indicates the moment when all the acids are saturated or neutralized, or, to put it more exactly, it denotes that the reaction has just turned alkahne. The number of cubic centimetres of the solution in the burette which have been used represents the acidity of the quantity of stomach contents which have been employed. A slight turbidity or yellowish color of the stomach contents does not interfere with the dehcacy of the reaction; it is also to be noted that the addition of the phenol-phthalein gives a slightly milky appearance to many stomach contents, f As a rule, the acidity of tion than is given in the text will And these methods fully described in the Hand- book of Volumetric Analysis, by Edward Hart; New York, John Wiley & Sons. In all these volumetric methods the metric system is obviously alone employed. —Ed.] * Where titrations are not made daily, Kleinert's burette will be found very con- venient. This burette differs from the ordinary form with glass stopcock in hav- ing the latter at the upper end above the zero mark of the scale, while the lower end is somewhat drawn out, and is ground, to permit its being closed with a glass cover. The burette is filled by dipping the lower end into the standard solution to be used and sucking at the upper end while the stopcock is open. By closing the latter the atmospheric pressure will keep the column of fluid in the burette. To titrate, we simply turn the stopcock above instead of below, as usual. After use, the lower extremity is closed with the well-greased glass cover. In this way we avoid the annoying drying of the stopcock, and also the alteration due to exposure to the air which occurs in the ordinary form in the drops of fluid in the lower end, if the burette is not in continual use ; this change is due to the formation of car- bonates. f In the test I have only described titration with phenol-phthalein. It is a well- known fact, to which Lippmann (Ueber den Sauregrad des Mageninhaltes bei An-](https://iiif.wellcomecollection.org/image/b21223026_0047.jp2/full/800%2C/0/default.jpg)
