106 SOLID FATTY ACIDS. 



alcoholic solution only faintly reddens litmus ; with a gentle heat 

 they expel carbonic acid from its salts; with most bases they form 

 insoluble salts, (the alkaline salts alone being soluble in water,) 

 and they have a strong tendency to form acid salts with bases. 



Very few of these acids have been found in the animal body ; 

 one of them, however, margaric acid, is the principal constituent of 

 all the fats yet found in the animal body. Associated with it is 

 another fatty acid, stearic acid, whose composition, although not in 

 accordance with the above formula, approximates so nearly to it 

 that it may be regarded as produced from 2 equivalents of mar- 

 garic acid, from which 1 equivalent of oxygen has been abstracted. 

 We place before our readers the whole group of these acids with 

 their chemical formulae, restricting, however, our observations, to 

 the two above named acids. 



Cocinic acid ., C 22 H 21 O 3 . HO. 



Laurostearic acid C 24 H 23 O 3 . HO. 



Myristicacid C 28 H 2J ,O 3 . HO. 



Palmitonic acid C 31 H 30 O 3 . HO. 



Palmitic acid C 32 H 31 O 3 . HO. 



Bogie acid C^H^Og. HO. 



Margaric acid C 34 H 33 O 3 . HO. 



Cocostearic acid .... C 35 H 34 O 3 . HO. 



Behenic acid C 42 H 41 O 3 . HO. 



Ceroticacid C 54 H 53 O 3 . HO. 



Stearic acid C 68 H 66 5 .2HO=2C 34 H 33 O 3 .HO - O. 



MARGARIC ACID. C 34 H 33 O 3 .HO. 



Chemical Relations. 



Properties. This acid has all the properties which we have 

 enumerated above as pertaining to this group. It crystallises from 

 a hot alcoholic solution in groups of very delicate nacreous needles, 

 which under the microscope appear interlaced like tufts of grass, 

 and arranged in ensiform plates, or grouped in star-like forms. 

 The acid, when thoroughly dried, fuses at 56 ; even when most 

 carefully heated in vacuo, it can only be partially distilled un- 

 changed, carbonic acid and margarone (C 33 H 33 O) being always 

 formed ; by prolonged contact with nitric acid, it becomes finally 

 decomposed into succinic, suberic and carbonic acids, and water. 



Composition. According to the above formula this acid con- 

 tains : 



