76 PHILOSOPHY OF ZOOLOGY. 
As these impurities are chiefly contracted in the prepar- 
ation of the oil, from the blubber and livers, it would be of 
consequence to examine, how far the various processes 
which have been recommended, might be employed with 
advantage, by the origimal manufacturer; or rather to de- 
vise means by which the oil might be extracted, without, 
at the same time, obtaining along with it, those substances 
which render it too thick for burning in lamps, and dis- 
agreeable on account of its smell. 
Many other substances secreted by different animals, 
deserve to be enumerated in this place, such as Castor, 
Civet, and Musk, but their characters are too unperfectly 
ascertained, to enable us to go into detail. The facts known 
concerning them, will be given when treating of the organs 
in which they are formed. 
9. Actds——The acids which we have now to enumerate, 
consist of various proportions of carbon, hydrogen, oxygen 

except a hot, greasy, soap-like scent. Then superadd half a pint of water, 
in which an ounce of salt has been dissolved ; and having boiled them half 
an hour, pour them into a proper vessel, and let them stand till the separa- 
tion of the oil, water, and lime be made, as in the preceding proeess.”— 
‘@ If the oil be required yet more pure. treat it after it is separated from the 
water, &c. according to the second process, with an ounce of chalk, a quar- 
fer of an ounce of pearl ashes, and half an ounce of salt.” 
The fourth process, ‘* Which may be practised alone, instead of process 
the first, asit will edulcorate and purify fish-oil to a considerable degree, so 
as to answer most purposes, and for process the third, when the whole is 
performed. 
« Take a gallon of crude stinking oil, and put it to a pint of water pour- 
ed off from two ounces of lime slacked in the air ; let them stand together, 
and stir them up several times for the first twenty-four hours ; then let 
them stand a day, and the lime water will sink below the oil, which must 
be carefully separated from them. ‘Take this oil, if not sufficiently purified 
for your purpose, and treat it as directed in process the third, diminishing 
éhe quantity of pearl-ashes to one ounce, and omitting the lime and chalk.” 
—See, likewise, some judicious observations in *¢ Scongssy’s Account of 
the Arctic Regions,” vol. ii. p. 408,--422. 
