122 THE ZOOLOGIST. 
weight of this quantity being about 170 kilogrammes, = about 
3 cwt. 40 lbs. :— sa 
A Blue Whale gives an average of about 70 casks of oil (not 
often less than 60, and occasionally up to 100). 
A Common Rorqual gives an average of about 25 casks 
(seldom less than 20, and reaching up to 35). 
A Humpback gives an average of about 15 casks (seldom up 
to 20, and rarely even 30). 
A Rudolphi’s Rorqual gives an average of about 5 casks,* 
and occasionally up to 7. 
Captain H. Hllevsen classes the oil somewhat differently to 
the classification given me by Captain Andreeff last year (Zool. 
1885, p. 140), viz. :— 
Class 1.—From the blubber of the back. That from the 
Common Rorqual is clearer than that from the Blue Whale, but 
they are mixed indiscriminately and considered as the same 
class. The oil from Humpback and Rudolphi’s Rorqual are 
slightly inferior to the other two species. 
Class 2.—From the blubber of the under side and tongue. 
Class 8.— From the intestines and second boiling of the 
blubber. 
Class 4.—From the bones and meat. 
The colour of the oil depends on the amount of boiling ; 
first class oil can be made as dark as fourth class by more 
boiling. The relative amounts of each class of oil can be 
approximately seen by the results obtained by Capt. Sérensen 
from 76 Whales in petroleum casks :—I1st quality (upper side), 
653; 2nd quality (under side), 209; 3rd quality (2nd boiling), 
80; 4th quality (krang). Most of these were boiled down at the 
Guano Factory, where, from 200 krangs, 900 casks 4th class oil 
were obtained (in addition to the guano). 
** Since the above was written I have looked over the MS. of a paper by 
my friend Professor Robert Collett, of Christiania, about to be published in 
the Trans. Zool. Soe. “‘ On the external characters of Balenoptera borealis,” 
in which he puts the average amount of oil obtained from individuals of that 
species at 15 barrels. This, perhaps, includes all the oil, while the above 
figures only include the oil extracted from the blubber, without reckoning 
the inferior quality from the krang, i.e., the flesh, bones, &c. Also, Professor 
Collett’s barrels may, perhaps, mean the Norwegian T’onde, a measure equal 
to about 30 gallons, instead of the American petroleum cask holding from 
40 to 44 gallons. 
