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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.