VOL. LXXVII.] PHILOSOPHICAL TRANSACTIONS. SIQ 



The spermaceti does not become rancid, or putrid, nearly so soon as the other 

 animal oils; which is most probably owing to the spermaceti being for the most 

 part in a solid state; and I should suppose that few oils would become so soon 

 rancid as they do, if they were always preserved in that degree of cold which 

 rendered them solid: neither does this oil become so soon putrid as the flesh of 

 the animal ; and therefore, though the oil in the cells appeared to be putrid before 

 boiling, it was sweet when deprived of the cellular substance. The spermaceti 

 is rather heavier than the other oil. 



In this animal we find 2 sorts of oil, besides the deeper seated fat, common 

 to all of this class; one of which crystallizes with a much less degree of cold 

 than the other, and of course requires a greater degree of heat to melt ft, and 

 forms perhaps the largest crystals of any expressed oil we know: yet the fluid 

 oil of this animal will crystallize in an extreme hard frost, much sooner than 

 most essential oils, though not so soon as the expressed oils of vegetables. 

 Camphire however is an exception, since it crystallizes in our warmest weather, 

 and when melted with expressed oil of vegetables, if the oil is too much satu- 

 rated for that particular degree of cold, crystallizes exactly like spermaceti. In 

 the ox the tallow, and what is called neat's-foot oil, crystallize in different de- 

 grees of cold. The tallow congeals with rather less cold than the spermaceti ; 

 but the other oil is similar to what is called the train oil in the whale. I have 

 endeavoured to discover the form of the crystals of different sorts of oil ; but 

 could never determine exactly what that was, because I could never find any of 

 the crystals single, and by being always united, the natural form was not 

 distinct. 



It is the adipose covering from all of the whale kind that is brought home in 

 square pieces, called flitches, and whicii, by being boiled, yields the oil on ex- 

 pression, leaving the cellular membrane. When these flitches have become in 

 some degree putrid, there issues 2 sorts of oil ; the first is pure, the last seems 

 incorporated with part of the animal substance, which has become easy of so- 

 lution from its putridity, forming a kind of butter. It is unctuous to the touch, 

 ropy, coagulates or becomes harder by cold, floats on water, not being soluble 

 in it; and the pure oil, separating in the same manner from this, floats above 

 all. What remains, after all the oil is extracted, retains a good deal of its 

 form, is almost wholly convertible into glue, and is sold for that purpose. The 

 cellular, or rather what should be called the uniting membrane in this order of 

 animals, is similar to that in the quadruped; we find it uniting muscle to muscle, 

 and muscle to bone, for their easy motion on one another. The cellular mem- 

 brane, which is the receptacle for the oil near the surface of the body, is in 

 general very different from that in the quadruped, as has been already ob- 

 served. 



