fatty Substances, and on their ComUnatlons with the Alkalis. 197 



This solution was only flisturbed at 4 1° of the centigrade. Upon 

 cooling it congealed into a solid mass: this mass had a greenish 

 shade, which became particularly evident in those parts of the 

 centre where a hole was made with a glass spatula. This phte- 

 nomenon seemed to be owing to the alcohol, for the colour dis- 

 appeared on the evaporation of this liquid. When the mar- 

 garine is deposited by a gradual cooling, from a solution which 

 is not saturated with it, it crystallizes in small needles which 

 luiite in stars. 



Action of Potash on Margarine. 



13. I now come to speak of one of the most remarkable 

 combinations of margarine, being that which it forms with potash. 

 It truly characterizes this substance, and leads me to examine 

 some points of the chemical doctrines respecting acidity. 



14. When exj)laining as above the ])rocess for purifying the 

 mother of pearl substance, I have observed that the latter gave 

 me S"07 gr. per cent, of potash ; but having found alkali in the 

 charcoal of distilled margarine, and being thereby convinced that 

 l^ie muriatic acid had not completely decomposed the mother 

 of pearl substance, I wished to make a new analysis of it. I 

 took tv.'o grammes of this substance perfectlv pure and dried. I 

 decomposed them by the muriatic acid, and kept the mar- 

 garine several times in fusion in acidulated water, in order to 

 take from it all its alkali. I obtained 0*2i5 gr. of muriate of 

 dry potash, which represented 0* 1(532 of potasli, admitting 64 of 

 base in the muriate of potash. The dried margarine weighed 

 1*865 gr. after having been fused. The ()'0282 exceeding the 



■weight of the matter analysed, ought to be attributed to water 

 remaining in the margarine, if the calculation of the muriate of 

 potash which we have admitted be exact. In order to assure 

 myself that the muriatic acid had dissolved all the potash united 

 to t'.'j margarine, I charred two grammes of mother of pearl 

 matter in a small platina crucible ; I lixiviated the charcoal, 

 and afterwards incinerated it: the atom of ashes which it left was 

 mixed with the lixivium of charcoal. I combined the whole 

 with the muriatic acid, and obtained 0'253 of muriate of pot- 

 ash, which confirms the first result. I think from this that we 

 maystate tlie following as the composition of the mother of pearl 

 substance : 



Margarine 91-84 100 



Potash 8-lG 8-88 



15. The pearly matter is soft to the touch, and has no per- 

 ceptible taste. 



10. When heated in the sand bath, it does not melt; it be- 

 N 3 gin? 



