ON COD-LIVER OIL. 141 
means of acetate of lead. The resulting lead-soap is to be 
treated with ether, which takes np oleate of lead and gaduin, 
and leaves undissolved the margarate of lead. The ethe- 
real solution is dark brown. If it be decomposed by sul- 
phuric acid, brown oleic acid is set free. The brown colour 
of this acid is owing to the presence of gaduin. To sepa- 
rate the latter, add excess of caustic soda to the oleic acid, by 
which oleate of soda is formed. This is insoluble in the ex- 
cess of caustic soda. It is to be dissolved in alcohol, and the 
alcoholic solution cooled below 32° 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 dry- 
ness. The alcoholic solution yields, on the addition of 
neutral acetate of lead, a copious precipitate, composed of 
C 35 H 22 0, Pb 0. If this lead salt be digested with carbo- 
nate 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 28S° Fahr., was found to have 
the following composition : C 35 H 23 O 9 . 
Gaduin is odourless, 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 pulverizable. It is insoluble in 
both nitric and hydrochloric acids. In sulphuric acid it dis- 
solves, and acquires a blood red colour, but from this solu- 
tion 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 already been made, is blackish-brown, pulverizable. 
