Mr Davidson on Fish Oils. 97 



Castor, while their apparent mutual distance is at least three 

 times as great. This circumstance, taken in connection with 

 the rapidity of their apparent proper motion, (which is 4-5".38 

 in R. A. and -f3".3 in declination,) affords a presumption of 

 their being much nearer to us, and renders 61 Cygni a fit ob- 

 ject for the investigation of Parallax." 



16. i Aquariiy R. Asc. 22^ m. S. Decl. 0^57. 



The two stars are of the 7th and 7| magnitude. In 1779-9, 

 its position was 71° 5' nf, and in 1825.73, 88° 56'. The mean 

 annual motion is 0*. 4484 retrograde. 



" As the proper motion of Z, Aquarii," says Messrs Her- 

 schel and South, " amounts to 0".173 annually, and yet the 

 stars of which it consists still retain the same distance, and 

 nearly the same relative situation with respect to each other, 

 this circumstance alone amounts to a proof of their mutual 

 connection, which their equal size corroborates, and renders it 

 exceedingly probable that they form a binary system." 



Aet. XX. — Observations on the properties tf some Fish 

 Oils^ and on the utility of Chloride of Lime in destroying 

 their putrid odour. By William Davidson, Esq. Sur- 

 geon, Glasgow. Communicated by the Author. 



i isH oils, with the exception of sperm oil, generally exhale a 

 fetid odour, and some are so putrid that they can only be used 

 for inferior purposes. Whale oil is generally more free of 

 fetor than seal, cod, and dog-fish oils ; and this is principally 

 owing to the superiority of the process for procuring the first ; 

 whereas in preparing the latter putrefaction is allowed to pro- 

 ceed too far before the oil is separated from the other animal 

 matters. It is no doubt an easy process to allow the animal 

 textures which contain the oil to be softened and decomposed 

 by the influence of the sun, but it is unquestionably inferior 

 to the application of artificial heat for that purpose. The dif- 

 ferent kinds of fish oils, though they agree as to their general 

 characteristics, yet are materially different in many other re- 

 spects. Whale oil, procured from the blubber of the Green- 

 land whale, is generally transparent, of a brownish colour, and 



VOL. Vll. NO. I. JULY 1827. G 



