CHEMICAL BASIS OF THE .AM .MA L BODY. ll'.t 



the first two in sweat. The first is an oily fluid, slightly soluble 

 in water, the other- an- -"lids ami scarcely soluble in water; they 

 are soluble in all proportions in alcohol and in ether. They may 

 be prepared from butter, and separated by the varying solubilities 

 of their barium salts. 



Laurie or Laurostearic acid. CnH 2s . COOH. 

 Myristic acid. C W H, 7 . COOH. 



These occur as neutral fats in spermaceti, in butter and other 

 fats. They present no points of interest. 



Palmitic acid, c, ,11 , 

 Stearic acid. C 17 H, 5 . ('< x H. 



These are solid, colourless when pure, tasteless, odourless, crys- 

 talline bodies, the former melting at 62 C., the latter at 69*2 C. 

 In water they are quite insoluble; palmitic acid is more readily 

 soluble in cold alcohol than stearic : both are readily dissolved 

 by hot alcohol, ether, or chloroform. Glacial acetic acid dissolves 

 tin-in in large quantity, the solution being assisted by warming. 

 They readily form soaps with the alkalis, also with many other 

 metals. The varying solubilities of their barium salts afford the 

 means of separating them when mixed : ' this method may also 

 be applied to many others of the higher members of this series. 



These acids in combination with glycerin (see below), together 

 with the analogous compound of oleic acid, form the principal 

 constituents of human fat. As suits of calcium they occur in the 

 and in 'adiporiiv,' and probably in chyle, blood, and serous 

 fluids, as salts of sodium. They are found in the free state in 

 decomposing pus. and in the caseous deposits of tuberculosis. 



Tin- '-\jsteiice of mararic acid. a> obtained from natural fats, in- 

 termediate to the above two. is not now admitted. >inci- Heintz has 

 shown 2 that it is really a mixture of palmitic and stearic acids. 

 Mar^aric acid possesses the anomalous melting-point of .V.)-9 C. A 

 mixture of iO part.- >tearic arid and l<> of pal mi I ic acid, melt- at d"'-;; . 

 A true mari:aric arid mav lio\\e\er In- prepared h\- replacing the group 

 <>H in eetyl-alcohol (C 16 H M . Oil) by the K roup ( '< )( >H. 



Wln-n animal (proteid) tissues are buried for some 

 tiim- in damp ground or othcr\vi.-e e\p ( i<ed t<> nn>i-nire j M the 

 absence of any free supply "t they aiv frequently found 



to have undergone a peculiar change 1-y which they are converted 

 into a waxy or fatty substance. This is known as adipocire. It 

 consists, not of true neutral fats, but of the ammonium, and in 

 some cases calcium, salts of the highest fatty acids palmitic and 



1 HHnt/., Poggemlorff'a Anital. d. Phys. . < '/, , I!. I \. n. S. 588. 

 at 



