100 Mr Davidson on Fish Oils, 4-c. 



ceti in its solubility in boiling alcohol, fixed oils, and oil of 

 turpentine, in its liquefaction by heat, and in forming sapona- 

 ceous compounds with the alkalies. It differs from pure sper- 

 maceti in its greater solubility in oils and alcohol, and in giv- 

 ing a much more abundant precipitate with acetate of lead. 

 Cod oil is, from universal experience, the only fish oil which 

 will answer all the purposes of the currier ; and it is reckoned 

 by many of them almost indispensable. This adipocirous 

 body, combined with the oil, is probably one of the causes of 

 its important qualities in rendering leather soft and pliant. 

 For, being carried in a fluid state into the texture of the lea- 

 ther, it will be intimately combined with it, and permanently 

 deposited there in a solid state by the influence of the mois- 

 ture and the tannin producing its coagulation. 



When a solution of chloride of lime is mixed with putrid 

 fish oil, and briskly agitated for a short time, it forms a thick 

 whitish compound, destitute of any fetor. In this state it is 

 totally unfit for burning, or, in general, for any practical ap- 

 plication. But if a portion of diluted sulphuric acid be add- 

 ed sufficient to decompose the chloride of lime, and if gentle 

 ebullition be employed for a short time, the lime is complete- 

 ly separated from the oil, and is precipitated in the form of 

 sulphate of lime, carrying the water along with it. 



The following is the process which I have generally adopt- 

 ed for destroying the putrid odour of fish oils : Dissolve 

 about one pound of chloride of lime in about one gallon 

 (imp.) of water, draw off the clear solution, and mix it tho- 

 roughly with about one hundred weight of putrid oil, then 

 add about three ounces of sulphuric acid previously diluted 

 with sixteen or twenty parts of water, and boil, with a gentle 

 heat, till the oil begins to drop clear from a spatula. After 

 the ebullition is finished, draw off the oil into a cooler, and 

 allow it to remain at rest for a few days. A vessel lined with 

 lead is less acted on by the acid ; but a copper or iron vessel 

 will answer the purpose perfectly well. The quantity of 

 chloride of lime must be varied according to the putridity of 

 the oil. It may be appreh«inded by some that the boiling 

 will injure the colour of the oil ; but it never does so where 

 the heat is properly applied ; for if there be a sufficiency of 



