30 Memoir on the Nature of fat Snlstances. 



ing to tlie regions wliich they occupy, and according to the age, 

 sex, and physical constitution of the individual. It is very hard 

 ill the neighbourhood of the kidneys, softer in the epiploon, the 

 mesentery, the intestines, and around other moveable viscera : 

 it is almost liquid when it coats the orbitary cavities. Certain 

 accidental dispositions also produce remarkable changes in the 

 consistence of the fat, as is observed in the stealoma, the old 

 herniae of the epiploon, and in certain sebaceous tumoilrs, v.'hich 

 are sometimes as hard as a calculus. 



On reflecting on this infinite variation in the consistence of 

 fat, and seeing besides that suet and oil seem to be the two «=■>;- 

 tremes of this consistence, it appeared to me that with these two 

 bodies mixed in various proportions, nature might produce that 

 diversity of fat bothes which we observe in organized beings. 

 Deeply" penetrated with this idea, which appeared specious at 

 least, I endeavoured to find among the chemical reagents some 

 substances capable of separating the suet and the oil which I 

 supposed to exist in all the fats, but I found none which could ef- 

 fect my purpose; when at last a very simple method presented 

 itself to my mhid, and fully confirmed my conjecture. It is 

 foimded on the physical property peculiar to oil, of being taken 

 up greedily by gray paper, which is not touched by suet or tal- 

 low, in its state of "purity. It was by applying this process to 

 the analysis of fatty substances that I succeeded in discovering 

 the two substances which compose them, arid in determinini^- 

 their respective proportions in the following substances. 



Melted Butter. 



This article was forcibly compressed for several days at the 

 temperature of zero, between several folds of coarse gray paper, 

 taking care to renew it until It was no longer stained: when 

 again pressed as at first, at a temperature of 15° Reaumur, a 

 white brittle matter was obtained, at least as compact as the 

 butter of cocoa or the hardest suet, of a very decided smell and 

 taste of suet. Suspecting that it might still retain some traces 

 of oleaginous matter, it was melted, and I mixed with it a small 

 ([uantity of volatile oil of turpentine : the matter, when har- 

 dened and pressed to absolute dryness in blotting-paper, pre- 

 sented a substance which was kept in fusion during some time : 

 when hardened, it was dry, broke with lustre, and melted at the 

 same degree of heat as beef suet, a temperature vvhich 1 found 

 to be 46" of Reaumur, while we find that mutton suet requires 

 a temperature of 49". The suet of cow butter is, in fact, similar 

 to that which exists in the varioTis parts of the body of this ani- 

 mal : a result which might lead to some physiological conse- 

 (picnccs. In order l«. obtain the oil u! butter, I moistened with 



warm 



