COD-LIVER OIL. 
647 
with those of bilifulvic acid, and he tells us that he was disposed 
to think that gaduin is primitive bilifulvic acid, and that the red¬ 
dish-brown substance, insoluble both in alcohol and water, which 
he (Berzelius) separated from bilifulvin by long and numerous 
operations, is only the insoluble modification of gaduin. This 
point, however, at present remains undetermined. 
Gaduin is contained in all the three varieties of oil examined 
by De Jongh. At first it is yellow, but under the influence of 
atmospheric air it acquires a brown colour. 
2. Fatty acids ; margaric and oleic acids .—These acids, as ob¬ 
tained from cod-liver oil, do not appear to differ in their nature 
and composition from the same acids procured from other sources. 
De Jongh analysed them in the form of margarate and oleate of 
lead. The results were as follow :— 
Margarate of lead. C 34 H 33 O , PbO. 
Oleate of lead . C 44 H 39 0 4 , PbO. 
3. Glycerine .—This was obtained by saponifying cod-liver oil by 
caustic soda. The residual lye was decanted from the soda-soap, 
saturated with sulphuric acid, and the sulphate of soda separated 
by crystallization. The residual glycerine was compared with 
glycerine procured from olive-oil and lead, and found to be darker 
coloured. All these kinds of glycerine were decolorized by adding 
basic acetate of lead to the glycerine solution, though they again 
became coloured when submitted to evaporation. 
4. Bile constituents .—When cod-liver oil is shaken with water, 
an emulsion is obtained, from which the oil slowly separates. The 
aqueous liquid becomes clear by filtration. That which had been 
obtained by shaking the brown oil with water was coloured and 
empyreumatic; but the other kinds of oil did not colour the water. 
The liquid invariably had a slightly acid re-action, and the oil 
which had been shaken with it was clearer, had a feebler odour, 
and re-acted less powerfully as an acid. By boiling the oils with 
water, the same results were obtained. By evaporation, the aque¬ 
ous fluids from all the three kinds of oil yielded a reddish-brown 
extract, which, softened by heat, was slightly soluble in water, was 
more soluble in ether, and completely so in alcohol. Alkaline so¬ 
lutions dissolved it, and acids threw it down again in the form of a 
reddish-brown flocculent precipitate. The extracts had a peculiar 
odour and a bitterish taste. The quantities obtained from the dif¬ 
ferent kinds of oil were as follow :— 
With cold water. With hot water. 
Pale oil. 0.607 per cent. ... 0.513 per cent. 
Clear brown oil . 0.890 “ ... 0.849 
Brown oil. 1.288 “ ... 1*256 “ 
When successively treated with ether, alcohol, and dilute spirit, 
all these extracts yielded the same results. 
