114 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Menai Strats Samples. 
Water and fat = 78°8 to 80°7. Water varies between 69°7 and 75°5, 
fat between 5:0 and 11:0 %. 
Morecambe Samples. 
Water and fat = 80°7 to 81°6. Water varies between 68-0 and 71:9, 
and fat between 9°6 and 14°6 %. 
W hitebatt. 
Water and fat = 80°3 to 81:1. Water varies between 78°4 and 80:4, 
fat between 0°7 and 1°9 %. 
Estimates of the water contents alone would, therefore, 
give measures of the fat contents accurate to about 1%, as 
a rule; thus percentage of fat = 80-0 — percentage of water. 
The paper thimbles containing the dried substance, were 
next taken from the weighing bottles. The cotton-wool plugs 
were inserted into the openings of the thimbles so as to prevent 
the detachment of any small fragments of tissue during the 
extraction. Carbon tetrachloride was used for the latter 
operation, and three or four extractions were usually made 
simultaneously. The solvent was distilled off from the extracted 
oil, and the latter was dried at 98° C. until the weight just 
appeared to rise—usually a matter of two to four hours. The 
thimble with the extracted material was then replaced in its 
weighing bottle, dried for at least 12 hours, and weighed. 
The water (by difference), the dried oil, and the dried residue, 
expressed as percentages of the original wet substance, usually 
added up to about 100-05 %. 
When the extraction was made on recently dried material 
the CCl, solution was always clear, and more or less brown 
in colour. Occasionally, the dried material was stored in 
stoppered or corked weighing bottles for two to six months, 
re-dried and re-extracted, and in such cases the extract was ~ 
always more or less turbid, something coming through the 
cotton-wool plug in the mouth of the extraction thimble. 
Some of this insoluble, detached substance was separated : 
it consisted of fine, needle-shaped crystals, insoluble in CCl, 
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