On the Action of Potash upon Cholesterine. 61 



throw a small piece of fused cholesterine into a vessel containing 

 water, that must afterwards be made to boil, (this is done to drive 

 away the air adhering to the surface of the body,) after which it 

 will be found to sink, and remain at the bottom of the vessel 

 even when the water is cold. I dwell thus much upon this, be- 

 cause I feel confident that there are other organic bodies that are 

 said to be lighter than water, but which are actually heavier; for 

 owing to the looseness of their structure, air insinuates itself be- 

 tween the molecules, and is afterwards held so firmly, that it is 

 impossible to drive it away by the ordinary means, J now re- 

 turn to the first distinguishing character between cholesterine 

 and the fats — the difference of the action of potash upon the two 

 bodies, 



Chevreul and others have shown, that if cholesterine be digest- 

 ed a great length of time in a boiling solution of potash, no 

 change takes place ; but here the cholesterine is not subjected 

 to the action of the potash under the same circumstances as the 

 fats; for in the case of the latter, the point of fusion being con- 

 siderably below that of boiling water, the force of aggregation 

 is in a great degree destroyed, and consequently does not oppose 

 itself to the chemical action ; whereas in the case of cholesterine, 

 its point of fusion being much higher than that of boiling water, 

 it remains solid, and therefore its force of aggregation opposes 

 itself strongly to the action of potash, (supposing one to exist.) 

 So then, the difference of the action of a solution of potash upon 

 these substances, is not such a strong mark of distinction as it 

 would at first sight appear to be, as it is impossible to subject 

 them to this action under similar circumstances. 



This fact is mentioned, not to show that cholesterine may be 

 a species of fat— far from it ; it is simply to attempt to exhibit, 

 that there is no stronger reason for supposing that cholesterine is 

 not a fat, because a boiling solution of an alkali does not act upon 

 it, than there is for considering spermaceti a fat, because it is act- 

 ed upon ; as here the spermaceti is in a state of fusion, one that 

 is favorable to this action, and the cholesterine solid, a state op- 

 posing this action. 



In an article on spermaceti published in this Journal, Vol. xliii, 

 p. 301, I stated my reasons at large for not believing this body 

 to be a fat, properly speaking, and at the same time explained 

 how I supposed an alkali to react upon it ; it was there ranked 



