264 ACTION OF POTASH UPON CHOLESTERINE. 



as the fats ; for in the case of the latter, the point of fusion 

 being considerably 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 acted upon ; as here the spermaceti is in a 

 state of fusion, one that is favorable to this action; and the 

 cholesterine solid, a state opposing this action. 



In an article on spermaceti 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 with athal and cholesterine. I then 

 also stated that although a boiling solution of an alkali might 

 not react upon cholesterine, still I had no doubt that the alkali 

 by itself, aided with a high temperature, would react upon it in 

 a manner similar to that which it did upon spermaceti. From 

 the kindness of M. Pelouze, who furnished me with a small 

 quantity of cholesterine, I have been able to examine into the 

 truth of this supposition. 



The first circumstance necessary to be observed in the exam- 

 ination of this reaction is to have the cholesterine intimately in 

 contact with the potash, and this is done by rubbing together 

 equal parts of the two substances in a mortar. The mixture 

 was placed in a watch-glass, and spread out so as to expose a 

 large surface to the air; the watch-glass was placed on a sup- 

 port in a copper vessel (the air contained in this vessel could 

 be brought to any required temperature). The experiment 

 being thus disposed, the vessel was heated, and by the time 



