APPENDIX. 681 
Caproic acid. CsHu:.COsH. 
Caprylic acid. C:H.s.CO.H. 
Capric acid.  C,His.CO.H. 
These acids enter into the fats of butter, from which they are readily 
prepared. ‘They are all soluble to but a slight extent in water, but 
readily in alcoho] and ether. They probably occur in the products of 
the sebaceous glands and the sweat, at least occasionally in some ani- 
mals. 
Laurostearic acid. C,,Has.COsH. 
Myristic acid. CisHa7.CO.H. 
They occur as neutral fats in butter, spermaceti, etc. 
Palmitie acid. C.sHs:.CO.H. 
Stearic acid. C.;Hss.CO.H 
These are colorless solids with melting-points, the former at 62° C., 
the latter at 69°2° C. Insoluble in water, but readily dissolved by hot 
alcohol, ether, or chloroform. With alkalies they form soaps; and with 
glycerin they, together with the oleates, make up the greater part of 
human fat. As salts of sodium (?) they occur in chyle, blood, serdus 
fluids. Combined with calcium they occur in the feeces and the adipo- 
cere of the buried cadaver. They are said to occur free in the caseous 
nodules of tubercle and in decomposing pus. 
The Oleic (Acrylic) Acid Series. 
General formula of series C,H» ,0, Several of the acids of this 
series occur as compounds of glycerin in various fats. They may be 
decomposed into acids of the acetic series. 
Oleic acid. C.eHs.Oc. 
The most important to the physiologist; is a colorless, oily liquid 
solidifying to a crystalline mass at 4° C. Soluble in alcohol and ether 
but not in water ; forms soaps with alkalies, 
The Neutral Fats. 
To understand this class of bodies it becomes necessary to bear in 
mind the relations of the acids of the fatty and oleic series to glycerin. 
Glycerin may be regarded as a tri-acid alcohol: 
OH H0.0C.C:sHa 0.CO.CisHs1 
CsHs j OH + HO.OC.CisHa = CsHs ¥ O.CO.CisHa + 3H30. 
OH HO0.0C.CisHa 0.CO.CisHa 
Glycerin. Palmitic acid. Glycerin tri-palmitate or palmitin. 
From which the relations of glycerin and a fatty acid to the neutral fat 
appear—i. e.,a neutral fat is the result of the replacement of the ex- 
changeable atoms of hydrogen in the tri-atomic alcohol (glycerin) by 
the acid radicles of the acetic or oleic series ; so that the neutral fats may 
be regarded as ethers, of which, in the nature of the case, there are theo- 
retically three ; but those only in which the most complete substitution 
has taken place are of importance from a physiological point of view. 
