BEN ZOIC ACID. 325 



when boiled with water, is resolved into carbonic 

 anhydride and protocatechuic aldehyde. 



2. Paratolylic aldehyde, C 8 1PO = C 6 H 4 j ^ Q Is 



obtained by distilling a mixture of calcium paratoluate 

 and formate. Colorless liquid, boiling at 204. Yields 

 paratoluic acid by oxidation. 



3. Cuminic aldehyde (Cuminol), C 10 H 12 O = 



{(^3TI7 

 CHO O ccurB > together with cymene, in oil of 



Roman cumin and in the oil from the seeds of Cicuta 

 virosa. Is obtained from these oils by shaking with 

 alkaline bisulphites, and decomposing the crystalline 

 compounds with sodium carbonate. Colorless oil, of a 

 pleasant odor, boiling at 237. When added to fusing 

 potassic hydrate, or boiled with alcoholic potassa, it 

 yields cuminic acid : in the latter case cuminic alcohol 

 is also formed. Yields by oxidation terephtalic acid. 



% E. ACIDS. 



a. Monobasic, Monatomic Acids. 



1. Benzoic Acid. 

 C 7 H 6 2 = C 6 H 5 .CO.OH. 



Occurrence. In a number of resins, particularly in 

 gum-benzoin; occasionally in the urine of herbivorous 

 animals. 



Formation. From monobrombenzene by the simul- 

 taneous action of sodium and carbonic acid ; the ethyl 

 ether, by the decomposition of a mixture of monobrom- 

 benzene and ethyl chlorocarbonate with sodium. By 

 the oxidation of all hydrocarbons, alcohols, aldehydes, 

 and acids in which only one hydrogen-atom of the 

 benzene is replaced by a monovalent carbon-group (for 

 instance, toluene, ethyl benzene, benzyl chloride, benzyl 

 alcohol, oil of bitter almonds, alphatoluic acid, hydro- 

 28 



