646 
COD-LIVER OIL. 
lead-soap is to be treated with ether, which takes up oleate of lead 
and gaduin, and leaves undissolved the margarate of lead. The 
ethereal solution is dark brown. If it be decomposed by sulphuric 
acid, brown oleic acid is set free. The brown colour of this acid is 
owing to the presence of gaduin. To separate the latter, add ex¬ 
cess of caustic soda to the oleic acid, by w r hich oleate of soda is 
formed. This is insoluble in the excess of caustic soda. It is to 
be dissolved in alcohol, and the alcoholic solution cooled below 
3*2° Fahr., by which the oleate of soda separates, leaving for the 
most part the gaduin in solution. By the addition of sulphuric 
acid, the gaduin is precipitated from its solution, 
Gaduin is a brown substance which is soluble in alcohol, but 
is rendered insoluble by evaporating its solution to dryness. 
The alcoholic solution yields, on the addition of neutral acetate of 
lead, a copious precipitate, composed of H^ O, Pb 0. If 
this lead salt be digested with carbonate of soda, it is decomposed, 
and a soda salt is obtained in solution, from which sulphuric acid 
precipitates a brown acid. This, when dried at 288° Fahr., was 
found to have the following composition, C 35 0 9 . 
Gaduin is colourless, tasteless, and of a dark brown colour. It 
is completely insoluble in water, but is for the most part soluble in 
both ether and alcohol. Its insoluble portion augments every time 
the solution is evaporated. When dry it is brittle and pulveriza- 
ble. It is insoluble in both nitric and hydrochloric acids. In sul¬ 
phuric acid it dissolves, and acquires a blood-red colour, but from 
this solution it is precipitated both by water and alkalies. It is 
soluble in alkalies. Diffused through water, and treated with 
chlorine, it becomes decolourized. In burning, yields an odour 
first of acetic acid, afterwards of cod-oil, and leaves behind a small 
quantity of ash. 
The insoluble modification of gaduin , to which allusion has al¬ 
ready been made, is blackish-brown, pulverizable, insoluble in 
water, alcohol, ether, and diluted sulphuric acid, but by concen¬ 
trated sulphuric and hydrochloric acid is converted into a black 
powder, without freely dissolving: in hot nitric acid it gradually 
and completely dissolves. It dissolves in alkalies, forming a red- 
coloured solution. In burning, it evolves the odour of acetic acid, 
and leaves about 0.822 per cent, of ashes. When dried at 
238° Fahr., its composition is C 39 H 26 0 12 = H 22 0 8 -|-C 4 H 3 
0 3 -f HO; that is, gaduin (C ls H 22 0 8 , HO) combined with acetic 
acid (C 4 H 3 H 3 ). But De Jongh’s formula scarcely agrees with 
his experimental result. He says that analysis gave him 7.04 per 
cent, of hydrogen, whereas his formula indicates about 7.3 per cent. 
Berzelius states that, when he read De Jongh’s account of gaduin, 
he was struck with the analogy of the reactions of this substance 
