ON COD-LIVER OIL. 
145 
Some chemists have failed to detect iodine in cod- 
Jiver oil. De Jongh says, that it is present in every genuine 
oil, but that the only certain mode of detecting it is to sapo- 
nify the oil, and carbonize the remaining soap. He con- 
firms Stein's remark, that neither by immediately carbo- 
nizing the oil, nor by saponifying it, and then decomposing 
the soap by acids, can the iodine be detected. It follows, 
therefore, that iodine exists in the oil neither in the free 
state nor in that of metallic iodide, but probably in organic 
combination — perhaps, as an iodic fatty acid. De Jongh 
determined the proportion of iodine by forming iodide of 
palladium; every 100 parts of anhydrous iodide of palla- 
dium was considered equivalent, to 70.34 parts of free 
iodine. * 
The largest amount of iodine found in genuine oil is less 
than 0.05 per cent. If the amount obtained be larger than 
this, fraud may be suspected. It is said by Dr. Martiny 
that some dishonest druggists have introduced iodine into 
the oil for the purpose of augmenting its commercial value. 
Nay, it is stated that an artificial cod-liver oil has been 
made by combining iodine with common fish or train oils. 
De Jongh detected bromine in the oil by Balard's process. 
The carbonized soap was digested with alcohol, and the 
alcoholic extract treated with chlorine gas and ether. Its 
proportion was estimated in conjunction with that of chlo- 
rine, as the quantity was too small to admit of accurate 
separation. 
The chlorine was determined by precipitating it as chlo- 
ride of silver from the watery extract of the carbonized 
soap. 
6. Phosphoric and sulphuric acids. — Phosphorus. — 
De Jongh determined the presence and quantity of these 
ingredients in the following way: The oil was saponified 
by potash, and the soap thus obtained decomposed by 
hydrochloric acid, by which the fatty acids were separated. 
From the solution the phosphoric acid was precipitated by 
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