Biochemical notes : laboratory work. First and second parts.

  • William John Gies
Date:
1906
Catalogue details

Licence: Public Domain Mark

Credit: Biochemical notes : laboratory work. First and second parts. 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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    in sufficient proportions for silicic acid to be precipitated by hydro- chloric acid. See 39. If a precipitate was produced on adding hydrochloric acid, observe whether sodium chlorid or any other soluble chlorid brings about the same result in a new portion of the liquid.* 12. Second group. As a rule nearly all the metals of the second group are entirely absent from normal biological liquids. Although traces of arsenic, for example, appear to be normally present in practically all animals and copper is contained in many, the proportions in which these elements occur are too trifling for detection by ordinary means (footnote, page 8). Besides, wherever arsenic and copper exist in animals ordinarily, they occur as a rule in organic, non-dissoeiable combinations. 13. Warm the clear acid liquid (ll), or the filtrate from (or ex- tract of) any precipitate that may have been formed by hydrochloric acid. Add a drop of hydrochloric acid to make certain that pre- vious (?) precipitation was complete, filter if necessary and treat the solution with a slight excess of hydrogen sulfid, preferably in aqueous solution. Cool. Proceed to 14. 14. Third group. Preliminary examination for phosphate and oxalate. Phosphate occurs almost universally, oxalate occasionally, in biological materials. Oxalate is always accompanied in organ- isms by phosphate. The presence or absence of phosphates and oxalates determines, as a rule, the method to be employed for the detection of the metals of the third, fourth and fifth groups.f 15. PreGipitation of phosphates and oxalates. To about 25 c.c. of the original solution % add a few drops of dilute nitric acid and boil for about a minute. Filter off, wash and reject any precipitate * Any albuminous matter that might be precipitated by hydrochloric acid would remain in solution on addition of sodium chlorid instead of hydrochloric acid. On the contrary the metals of the first group would be precipitated. See footnote, page 9. t Silicates and fluorids, which occasionally occur in minute proportions in biological liquids, affect slightly the method of procedure at this point. Their influence need not be taken into account, however, except in very special cases. % Blood and other albuminous liquids should be diluted with several volumes of water before adding the nitric acid. If any of the metals of the first or second groups were detected in tests 11 and 13 they must be removed from the solution before proceeding to the separation of the metals of the third, fourth and fifth groups. After the elimination of such heavy metals hydrogen sulfid should be compUlely removed from the final filtrate by boiling. Determine this matter accurately by testing the vapor with wet lead acetate paper. The solution is then in proper condition for the treatment indicated above, under 15.
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