On the immediate principles of human excrements in the healthy state / by William Marcet ; communicated by H. Bence Jones.

  • William Marcet
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: On the immediate principles of human excrements in the healthy state / by William Marcet ; communicated by H. Bence Jones. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    margaric acid into a neutral margarate of lime. The quantitative analysis of the deposit was effected by boiling it with potash, and decomposing the soap by means of hydrochloric acid, for the pm-pose of precipitating the margaric acid. The Avhole being thrown on a filter, the precipitate was washed until the washings had ceased to exliibit an acid reaction and produce a cloudiness in a solution of nitrate of silver; the fatty acid was dried on filtering-paper, and finally dissolved in ether; the ethereal extract being evaporated to dryness in a weighed beaker, the weight of the residue could be easily ascertained. The phosphoric acid and lime were determined in the filtrate from the margaric acid precipitate, the phosphoric acid with perchloride of iron and sulphate of magnesia, and the lime with oxalic acid. The follomng Table shows the result of the analysis, together with the quantity of margaric acid necessary to combine with the amount of hme, exceeding that which could possibly have been combined originally Avith the phosphoric acid: these numbers were obtained by calculation, according to the for- mula for the neutral margarates,— C3,H33 03 + MO. Pound. Calculated. Lime. Phosphoric acid. Margaric acid. Margaric acid. 1. 0-0021 0-015 0-083 0-074 2. 0-040 0-031 0-230 0-112 3. 0-058 0-042* 0-205 0-196 4. 0-031 0-023* 0-100 0-102 These results show that the lime, phosphoric acid and margaric acid found in the deposit under examination, existed as phosphate of lime and margarate of lime, and consequently assumed this form in excrements f. From the difficulty of extracting fatty acids perfectly pure and colourless, without experiencing more or less loss of substance, when they are mixed up Avith animal colour- ing-matters and other impurities, it is next to impossible to obtain mathematically exact results in such analysis. In analyses No. 1 and No. 3, the quantities of margaric acid found were slightly above the proportion determined by calculation, which resulted from the presence of impurities; these could not have been removed without the loss of more or less of the acid. In analysis No. 2 the margaric acid Avas highly coloured and impure, AA'hich accounts for its proportion being considerably aboA'e Avhat it ought to have been. In analysis No. 4, the margaric acid obtained being comparatively pure, the result was very conclusive. The alcoholic extract of excrements filtered from the deposit just described, four or * In analyses 3 and 4, the quantity of phosphoric acid was obtaitied by calculation. t It is very remarkable that these salts should have dissolved in the boUing alcoholic extract of faeces, and lost their property of dissolviag in boiling alcohol, after having been collected on a filter; which cir- cumstance is probably owing to the acid reaction of the alcoholic extract. The same observation applies to the margarate of magnesia.
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