OB Mr Davidson"*s observations on the 



not sluggish when agitated in a phial. When agitated with 

 cold water it is rendered of a whitish colour, but the water 

 -soon separates, and it regains its former transparency. When 

 ^ater is boiled along with it a cloudiness is produced ; and 

 when diluted sulphuric acid is boiled with it a scanty preci- 

 pitate of brownish flocculi is deposited at the bottom of the 

 oil. Seal oil, procured from the fat of the seal by the sponta- 

 neous decomposition of the animal textures, is pale and trans- 

 parent, and is generally thinner and more fluid than whale oil. 

 When agitated with cold water it is only rendered cloudy, and 

 very speedily regains its usual transparency. When diluted sul- 

 phuric acid is boiled in contact with it a slight cloudiness is pro- 

 duced, which is gradually deposited at the bottom of the oil. 

 Cod oil, procured from the liver of the cod-fish by the spon- 

 taneous decomposition of the animal textures, is generally of 

 a dark-brown colour, sometimes pale, and is a thicker and 

 more tenacious oil than any of the other kinds. It generally 

 deposits at the bottom of the casks a considerable quantity of 

 brownish flocculi, technically called *' foots" by oil-dealers. 

 Dog-fish oil is similar in its properties to cod oil ; but in ge- 

 neral exhales a most insupportable odour. Cod oil, when 

 heated to 212° F. or even considerably beyond that point, does 

 not throw down any precipitate. When cold water is agitated 

 with it, it assumes the appearance of an emulsion, and a por- 

 tion of flocculi is deposited at the bottom of the oil. Water, 

 diluted sulphuric acid, or decoction of galls boiled in contact 

 with it, causes a large quantity of brownish flocculi to be se- 

 parated, and gradually precipitated. Water which has been 

 boiled in contact with cod oil leaves scarcely any residuum on 

 evaporation, and gives no precipitate with tincture of galls, ace- 

 tate of lead, corrosive sublimate, nitro-muriate of tin, or nitrate 

 of silver. The flocculi are again soluble in the oil from which 

 they were separated, in oil of turpentine, and in boiling alcohol, 

 which latter on cooling again deposits a considerable portion of 

 them. They seem to possess the same properties as those which 

 are spontaneously deposited in the original oil casks. Alco- 

 hol boiled in contact with cod oil extracts the greatest pro- 

 portion of this flocculent substance ; for when water is after- 

 wards boiled in contact with it, a very small deposit is obtain- 



11 



