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Volume 52, 1920
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Art. VI.—Sting-ray-liver Oil.

[Read before the Wellington Philosophical Society, 3rd December, 1919; received by Editor, 31st December, 1919; issued separately, 4th June, 1920.]

Mr. Hoyle, of Thames, conducted some experiments in the extraction of oil from sting-ray livers, and a quantity of about 8 oz., which he obtained from the liver of a single fish, was examined at the-Dominion Laboratory in September, 1918. The sting-ray was probably Dasybatis brevicaudatus (Hutton).

The oil was compared with cod-liver oil, with the following results:—

Sting-ray-liver Oil. Cod-liver Oil.
Specific gravity at 15.5° C. 0.927 0.923–0.930
Saponification value 189 182–187
Iodine value 156.5 137–167
Refractive index at 15° C. 1.4796 1.4800
Unsaponifiable matter (per cent.) 3.7 0.6–2.6
Hexabromides (per cent.) 45 42.9

The oil was free from rancidity, and quite palatable. It contained some “stearine,” which made it cloudy at low temperature, and which, in the case of cod-oil, is usually removed by cooling and filtering.

If the present sample were similarly treated the product would scarcely be distinguishable in appearance or composition from good cod-liver oil.