078 M. Chevreul on Fatty Bodies, and [Oct. 



which is not the case when the margarate of potash is dissolved 

 in alcohol of a specific gravity above 900. 



This discovery induced M. Chevreul to examine what was the 

 influence which water exerts on alcohol of the specific gravity 

 of -791, holding the super-margarate of potash in solution. It 

 was observed that when the wateiy extract of litmus is added to 

 a solution of the super-margarate in this kind of alcohol, a blue 

 precipitate is produced, which was not dissolved, even when the 

 alcohol was warm ; for when it was filtered at the boiling heat, 

 blue flakes were left upon the filter, and the fluid passed colour- 

 less. In order to know the extent, of this property of litmus, of 

 oeing insoluble in concentrated alcohol, - 02 parts of margaric 

 acid were dissolved in five parts of alcohol of the specific gravity 

 of -791, to which was added 0"26 parts of the watery extract of 

 litmus, when the fluid immediately became of a reddish purple. 

 It was boiled and filtered, the fluid passed through of a red 

 colour, and there remained flakes of a deep red upon the filter. 

 As the insolubility of the litmus in alcohol does not prevent 

 the margaric acid which is dissolved in this fluid from taking 

 the potash from litmus, we may conclude that there is some 

 other power, besides its insolubility, which prevents the excess 

 of margaric acid in the super-margarate of potash, when dis- 

 solved in alcohol, from neutralizing the potash of litmus : this 

 power is supposed to be the affinity which absolute alcohol has 

 for fatty bodies in general. This affinity rapidly decreasing in 

 proportion as more and more water is added to the alcohol ; and 

 the affinity of alcohol for potash rather augmenting than diminish- 

 ing by the presence of the water, it may be supposed that 

 absolute alcohol, when it dissolves the super-margarate of potash, 

 will tend to diminish the action of margarate of potash on mar- 

 garic acid less than diluted alcohol, which has less affinity for 

 the excess of margaric acid. Consequently this action of water 

 upon alcohol, joined to that which it has upon the extract of 

 litmus, determines the excess of margaric acid to leave the 

 neutral margarate to combine with the alkali of the litmus. 

 These considerations on the mode in which litmus acts, lead to 

 the conclusion that its indications are relative only, and that we 

 cannot deduce any positive consequences from them until we 

 have taken into account the circumstances under which the 

 bodies are placed. 



The second part of the seventh memoir of M. Chevreul is 

 on the oil ©f the Delphinus globiceps.* 



The first chapter contains an account of the properties of the 

 oil. It was extracted by a sand-bath from the cellular texture in 

 which it was contained. It was of a light lemon colour, its 

 odour is said to resemble that of fish combined with the smell of 

 leather soaked in fat ; its specific gravity at the temperature of 



* Ann. de Chim. et Phys. vii. 264. (March, ISIS.) 



