2o CHEMICAL CONSTITUENTS OF BODY AND FOOD. 
Mohr gives the proportion of the acids in marrow fat as — palmitic acid, 22 ; 
stearic acid, 10; and oleic acid, 63 per cent. 
Among the exceptional forms of fat are the following : — 
Spermaceti, obtained from the sperm whale. This fat sets into a solid, 
white crystalline mass, melting at from 30° to 50° C. Its chief constituent 
is the palmitate of cetyl alcohol, or ethal (( \ H. !3 OH). This alcohol is the 
one from which palmitic acid is derived in the same way as acetic acid 
is derived from ethyl alcohol. Spermaceti contains also small quanti- 
ties of compounds of lauristic, myristic, and stearic acids, with the 
radicles of the alcohols lethal (C r >Ho S OH), methal (C 14 H, OH), and 
stethal ((VH.^OH). 
Beeswax contains three chief constituents: — 
(1) Myricin; this is its principal constituent; it is the palmitate of 
myricyl alcohol (( \JT C1 ( )H) : (2) Cerotic acid (( '., : M : ,^ U : and (3) Cerolein, 
which is probably a mixture of several substances. 
Chinese wax is chiefly the cerotic acid compound of cerotvl alcohol 
(a 7 H : ,OHV 
Adipocere is the name given to a waxy substance which replaces the 
muscular tissue in corpses buried in damp soil, or which have been 
allowed to remain in water some time after death. It consists chiefly 
of the calcium soaps of palmitic and stearic acids, and in some cases of 
acid ammonium soaps also. 2 Hoppe-Seyler 3 considered that the change 
is the result of a ferment action. 
Lipochromes, Lecithin, Cholestepix. 
Lipochromes. — This name is given to the pigments which occur in 
fat and fatty tissues. They are mostly yellow or yellowish red. They 
include the pigment of the blood serum (serum lutein) and of the corpus 
luteum ; the chromophanes or coloured oil globules of the retinal cones : 
tin: yellowish pigment in butter, adipose tissue, and egg-yolk; tetronery- 
thrin, a reddish pigment, found in many invertebrates; and several 
vegetable pigments, such as carrotin, which is found in carrots and 
tomatoes. The lipochromes have been separated by their various 
solubilities after saponification; they give various colour reactions, such 
as a greenish-blue colour with iodine and sulphuric acid, and a green 
colour with nitric acid ; they show absorption-bands towards the 
violet end of the spectrum, and especially in the region of the F line. 
Nothing is known about their chemical constitution ; carrotin, which 
has been examined more fully than the others, has been assigned the 
formula C 18 H 24 by Husemann, and C 26 H 3S by Arnaud. 4 
1 On these rarer forms of fat and wax, see Liebermann, Per. d. deutsch. chem. GescUsch., 
Berlin, 18S5, Bd. xviii. S. 1975. 
- Quain, Med.-Chir. Tnnix., London, 1S50. p. Ill ; Virchow, Vcrltandl. d. phys.-med. 
GescUsch. in Wihrzburg, Bd. iii. : Wetherill, Journ. f. prdkt. Chem., Leipzig. Bd. lxviii. 8. 
2b' : K. B. Lehmaun, Cent ml hi. f. Agric. Ch< „/., Leipzig, 1889, S. 66. 
3 "Physiol. Chem.,'" Strassburg, S. 119. According to some authors, its formation is 
brought about by micro-organisms (Jacobsthal, Arch. f. d. gcs. Physiol., Bonn, 1893, Bd. 
liv. S. 499. 
4 The principal papers on lipochromes are the following : — On lutein — Thudichum, 
Ccntralbl. f. d. mo I. JVissensch., Berlin, 1869, Bd. vii. S. 1. On colour reactions of 
luteins — Thudichum, loe. eit. ; Piccolo and Lieben. Gior. eh sc. nat. ed. ccon., Palermo, 
vol. ii. p. 258 ; Caprarnica, Arch. f. Physiol., Leipzig, 1877, S. 283.; Schwalbe, 
"Handb. d. ges. Augenheilkunde," Leipzig, 1874, Bd. i. S. 414. On chromophanes 
— Kiihne and Ayres, Journ. Physiol., Cambridge and London, 1878, vol. i. 
p. 109 ; Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, Bd. i. Heft 4. On 
