ACIDS AND ALCOHOLS 141 



Lactic Formed by the bacterial fer- 



C 3 H 6 3 (CH 3 -CH(OH) - mentation of milk sugar (lac- 

 COOH) tose), also by bacterial fer- 



mentation in sauer kraut and 

 ensilage. 



Oxalic Free or as acid or neutral salts 



C 2 H 2 4 (COOH-COOH) of Ca, K or Na in Oxalis, 



Rumex, Rheum, etc. Very 



abundant as Ca salt in. the 



form of crystals. 



Succinic In green grapes, and in 



C 4 H 6 4 (COOH-CH 2 -CH 2 various Papaveraceae and As- 

 -COOH) terales. 



Dextro-tartaric Free and as acid salt of K in 



C 4 H 6 6 (COOH-CH(OH)- fruit of grapes and in other 

 CH(OH)-COOH) fruits. 



Malic Very widely distributed as 



C 4 H 6 5 (COOH-CH 2 -CH- free acid in fruits, e.g. apple, 

 (OH) -COOH) barberry, grape; hi leaves of 



Crassulaceae, etc. 



Citric Free in fruits of Citrus 



C 6 H 8 7 (CH 2 (COOH) -C- (orange, lemon, etc.), goose- 

 (OH) (COO H)-CH 2 (COOH)) berry, etc. 

 Benzoic In fruit of cranberry and in 



C 7 H 6 2 (C 6 H 5 (COOH)) various gums. 



Salicylic In flowers of Ulmaria and as 



C 7 H 6 3 (C 6 H 4 (OH)(COOH)) an ester in Wintergreen. 

 Gallic In insect galls, tea, etc. 



C 7 H 6 5 (C 6 H,(OH) 3 (COOH)) 



Gallotannic (tannin) In great abundance in many 



CuHioOg (= two molecules of plants; the chief tanning sub- 

 gallic acid united, less H 2 0) stance. 

 Alcohols. 



Methyl As an ester in some fruits; 



CH 4 (CHs(OH)) produced by dry distillation of 



wood. 



Ethyl Produced in the anaerobic 



C 2 H 6 (CH 3 -CH 2 (OH)) stage of respiration of glucose. 



The chief product (together 



with C0 2 ) of fermentation of 



glucose by yeasts. 



