476 DISCOVERY REPORTS 



APPENDIX II 



A NOTE ON THE OIL CONTENT OF BLUBBER 



By a. J. CLOWES, A.R.C.S., M.Sc. 



This investigation was made in order to see if there was any variation in the fat content 

 of whale blubber throughout the season, which variation, if present, might be taken as 

 some indication of the condition of the whale. It is well known that the blubber on a 

 whale varies in thickness in different parts of the whale, being thickest behind the dorsal 

 fin and thinnest on the back behind the head, but whether the actual oil content (ex- 

 pressed as percentage by weight) varies in different positions is not known. In all the 

 experiments made the blubber was always cut from the same position on the whale as 

 described below. 



A piece of blubber, roughly measuring a six-inch cube, was cut from the flank opposite 

 the tip of the dorsal fin. This place was used in "thickness" measurements. Two 

 parallel strips, about 5 cm. long and i square cm. in cross-section, were cut from this 

 cube of blubber with the aid of a razor and then weighed and placed in a weighed 

 soxhlet extraction thimble. The sections were always taken from the skin inwards, the 

 skin being trimmed off before the strip of blubber was weighed. All handling of blubber 

 was done with forceps and no attempt was made to wipe off free oil. 



The method used was one of continuous extraction of the blubber by carbon tetra- 

 chloride in a soxhlet apparatus. Carbon tetrachloride was chosen because in addition 

 to the primary object of dissolving fat, it was more easy to recover than petroleum- 

 ether, or other solvents. 



Carbon tetrachloride extract may be regarded as synonymous with fat content, 

 although a small amount of substances other than true fats are extracted with the fat. 

 It was considered that as the investigation was to be made on a number of whales, 

 this would not matter for the comparative result which was desired. The strips of 

 blubber, after being cut and weighed in the soxhlet thimble, were placed on a glass dish 

 and cut into thin sections by means of a razor and forceps. This was done in order to 

 accelerate the penetration of the cells of the blubber by the solvent. Any oil liberated 

 during this process was washed into the soxhlet flask with carbon tetrachloride. The 

 same procedure was adopted in all experiments made and by this means the experi- 

 mental error was cut down to a constant minimum. 



The following figures from a preliminary test give some indication of the amount of 

 oil extracted each two hours over a period of ten hours' constant extraction. 



Weight of sample of blubber = 5-7920 grm. Oil extracted : 



In ist two hours 3-9024 grm. In 3rd two hours 0-1718 grm. 



In 2nd two hours 0-3955 grm. In 4th two hours 0-0572 grm. 



In 5th two hours 0-0146 grm. 



