The three kinds of cod liver oil : comparatively considered with reference to their chemical and therapeutic properties / by L.J. de Jongh ; translated from the German, with an appendix and cases, by Edward Carey.

Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: The three kinds of cod liver oil : comparatively considered with reference to their chemical and therapeutic properties / by L.J. de Jongh ; translated from the German, with an appendix and cases, by Edward Carey. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    16 to 20 hours) until it becomes of a dark brown colour, and is quite clear; this is the brown oil, which is strained, and the residuum in the kettles is used for manure. 2. Exactly the same method is adopted in making the liver oil from the seij-fish as with the livers of the dorse, and only differs in the quality; the dorse oil remains liquid and clear in a cold temperature, and is easier obtained than the seij-fish oil; while the latter, the pale as well as the brown, congeals at a reduced temperature. 3. Liver oil from the pollack. The liver of this fish is the fattest, and gives the most oil; in the preparation the same method is adopted as with the dorse and the seij-fish, both the pale and the brown oil are obtained in the like manner; ias, however, a pretty long time is required before the livers putrefy, they are in the habit of putting them, fresh as they are, in the iron kettles to dissolve by a moderate heat, and then pouring off the clear oil, which is the light-brown oil; what remains in the kettles is boiled and yields the brown oil. The so-named light-brown hver oil, is for the most part, procured by moderate heat from the livers of the pollack; in great measure, however, it is obtained from the dorse and the seij-fish hver, and indeed from these two last sorts, with- out the application of heat, so that in this case both are mixed together; the colour of the light-brown oil arises in part from its remaining too long on the hvers before it is poured off, partly after the pale is poured oft^ from the resi- duum being left standing some time in order that still more may be procured; it thus acquires a darker colour, and is named the light-brown oil. The export of the dorse is the most considerable, then that of the seij, and least of all, the poUack; but for some years past, the fishermen (at least on this coast) pursue this fishery more than they did formerly.
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