The oleates in cutaneous diseases / by Henry W. Stelwagon.

  • Henry Weightman Stelwagon
Date:
[1884]
Catalogue details

Licence: Public Domain Mark

Credit: The oleates in cutaneous diseases / by Henry W. Stelwagon. Source: Wellcome Collection.

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    lead oleate is decanted and shaken with diluted hydrochloric acid (i to 7); this separates the lead chloride and leaves a benzin solution of oleic acid, which, after the expulsion of the benzin, gives an acid that is well adapted for the manufacture of the oleates. The oleic acid so obtained is of a light-yellow color, readily miscible with 92 per cent, alcohol in all proportions without causing turbidity. (Wolff.) The oleate of sodium may be obtained by saponifying the acid with caustic soda. A solution of this and a solution of a metallic salt brought together, will give a precipitate of the oleate. As this method of obtaining the oleates by double decomposition is, however, somewhat expensive, the following method may be employed : One part of castile soap (sodium oleo-palmitate) is dissolved in eight parts of water; this is allowed to stand for twenty-four hours, when there will be a considerable deposit of sodium palmitate. The super¬ natant liquor containing mostly sodium oleate, is drawn off and de¬ composed with a concentrated solution of a metallic salt, which, if obtainable, should contain no free acid to prevent the formation of free oleo-palmitic acid. The heavy deposit of oleo-palmitate so de¬ rived is strained off, pressed out in the strainer, and the adherent water evaporated over a water-bath; afterwards it is dissolved in about six to eight times its quantity of petroleum benzin, and the insoluble palmitate is left to subside while the solution of the oleate decanted therefrom is filtered off. The benzin evaporated will yield an oleate that is a chemical combination, and one that will remain stable and efficacious. (Wolff.) The oleates, whether made by the direct combination of the acid with the oxides or by the process of double decomposition, are fixed salts, and the designations of five per cent., ten per cent., etc., oleates, are misnomers, and wholly incorrect. The so-called per cent, oleates are solutions of the oleates in free oleic acid; for example, the so- called ten per cent, oleate of mercury is so named for the reason that ten parts of mercuric oxide are added to ninety parts of oleic acid, and combination allowed to take place. The oxide, however, only re¬ quires a certain proportion of the ninety parts of the oleic acid for the production of the oleate, so that there must be a considerable quantity of the acid which is not needed for the combination ; in other words, the so-called ten per cent, mercuric oleate (and the same ap¬ plies to the other per cent, oleates) is a solution of the oleate in free oleic acid. It will be readily seen that this manner of speaking of the oleates, therefore, is not only misleading, but erroneous, and should be dis-
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