32 Memoir on the Nature ofjai Sulstances, 



Of the Fat of Pork, or Lard, 



Like melted butter and the other fati, that of pork has been 

 hitherto regarded as a homogeneous body. M. Vogel consi- 

 dering it as such, submitted it to a series of experiments in a 

 memoir particularly directed to the examination of this sub- 

 stance*. Recent hogs-lard, well purified, was long pressed in 

 gray paper, as we have directed in the case of butter, and a suet 

 was obtained of the consistence of soft waxj as this suet seemed 

 to me still to retain some oil, it was purified by melting it in oil 

 of turpentine, and by submitting the mixture when cold to new 

 compressions in gray paper, there remained a sebaceous matter, 

 which was I.eld in fusion some time to extract the small quan- 

 tity of oil of tmpentine which it might contain. This absolute 

 suet at the ordinary temperature of the atmosphere is dry, brittle, 

 and inodorous, like the other suets in their state of purity ; but 

 it differs from them in being almost transparent or semi-dia- 

 phanous like certain calcedonies; it is softened or reduced by the 

 fingers with great difficulty, although more easily than beef suet, 

 and has not such a greasy appearance, but it is soft and soapy 

 to the touch like whale fat, like which it leaves a br'lliant lustre 

 when it '^ rubbed on bodies: in these respects it resemblet 

 spermaceti : it has, however, but a grainy crystallization, not 

 decid^ d ; and it is less soluble in boiling alcohol, although the 

 latter takes up enough to make the liquid turbid on cooling, and 

 there are separated flakes of greasy matter on the addition of 

 lutre. 



The suet of pork requires for its fusion a temperature a little 

 higher than that wliich is necessary for melting whale fat. 



The same suet, like all those obtained from the different fatty 

 substances, undergoes under tiie action of the acids and alkalis 

 a very r-eniarkable alteration, in so much as it is converted into 

 two substances which did not ''xist before ; namely, adipocire 

 and oil. both extremely soluble in 'varm alcohol. This trans- 

 fonnation is entirely and immediately affected by pouring into 

 one t'Jit of pork suet melted, half a part of sulphuric acid, and 

 bv immediately diluting the mixture with a quantity of boiling 

 water in order to take up the acid and to separate the two fat 

 matters newly formed, which we shali presently make known. I 

 aha'l content myself with observing at present, that the suet of 

 pork on being converted into adipocire and oil is susceptible of 

 forniini; >vith the sulphvnic acid a soapy combination sufficiently 

 intimate, and even solulde in water like soap, which does hot 

 p^eci^eiy happen on treating beef or mutton suet in the same 

 way, although all the fat substances, in changing their iiature, 



* Annala de Chimie, tome Iviii. p. 154. 



also 



