254 Mr Davidson on the Adulteration of Fixed Oils. 



solidified in three hours, and, in twenty-four hours, was as 

 hard and about the same colour as pure oil of olives treated in 

 the same manner. 



10 per cent, of rape oil, added to dolphin oil, and treated by 

 the acid nitrate of mercury, renders it softer and more of 

 an orange tint ; but the indication is not sufficiently precise 

 to render it of any use as a test, without a comparative ex- 

 periment with pure dolphin oil. 



Whale Oil, however, can be detected with more certainty. 

 I find that 10 per cent, of whale oil, mixed with dolphin oil, 

 prevents the complete solidification, and a portion of oil re- 

 mains fluid, and the rest is more soft and brown, than pure 

 dolphin oil treated in this manner. 



Sperm Oil is solidified in from one to two days to the con- 

 sistency of thick honey, by the acid nitrate of mercm-y, and is 

 of an orange colour when the oil is pale, but when it is high 

 coloured, it is rendered brownish. 



20 grs. of rape oil were mixed with 80 grs. of pale coloiired 

 sperm oii, and treated with y j of the acid nitrate of mercm'y ; 

 its complete solidification was prevented, a very small portion 

 remaining fluid, whUe the whole was rendered of a deep red- 

 dish-browai colour. Sperm oil is very frequently employed 

 for greasing machinery, and when adulterated with rape oil, a 

 practice which is exceedingly frequent, is productive of very 

 injm-ious consequences. It is, therefore, a desideratum of 

 great practical importance to detect this sophistication ; but 

 the acid nitrate of mei'cury cannot be considered sufficiently 

 precise in its indications. 



Whale Oil, Cod Oil, and Pale Seal Oil. — These oils were 

 each separately treated in half-ounce phials with -^^ of the acid 

 nitrate of mercury, and its operation on them all was found 

 to be very similar, viz. that it causes the solidification of a 

 small portion of the oil, which has a dirty orange colour, and 

 which falls to the bottom of the phial, while the remainder 

 retains its fluidity, and is rendered of a dark brownish-red 

 colom-. These last experiments were originally tried several 

 years ago, with the view of discovering some indication for 

 the discovery of the falsification of these oils with linseed 

 qI\^ a practice whicli was carried on to a great extent in Ghs- 



