125 



from the potash or soda solution by acids ; becomes red with con- 

 centrated sulphuric acid, with concentrated nitric acid bro^vn and 

 resinous. Iodine has no action on it. The crystals of M. melt 

 at 80° to 82°, becoming amorphous; at 125° they emit white 

 vapoui-s which condense to oily drops and consist partly of un- 

 altered M. and partly of a resinous mass.] 



Maleic Aci(l=EQuisETic Acid. 



Malic Aci(l=C4 Ho O4 + HO. A widely-distributed substance, 

 and perhaps the commonest of all vegetable acids. It has been 

 observed in all parts of plants, principally and most abundantly in 

 fruits, especially in uni-ipe and acid ones. Several of the acids that 

 have been foimd in plants and are described under different names, 

 are probably nothing but Malic acid, as for instance Igasuric acid 

 of the seeds of Strychnos nux vomica, and Braconnot's Fungic acid. 

 When a vegetable extract yields with lime-water no turbidity 

 either cold or hot, the presence of Malic acid may be inferred ; yet 

 it may even possibly be present when a turbidity does ensue, 

 because one plant often contains two and more organic acids. 

 Malic acid is distinguished and prepared on a small scale in this 

 manner. Neutralise the respective liquid when acid with 

 ammonia, jjrecipitate with acetate of lead, leave to subside for 

 one day in a cold place and collect the deposit on a filter, wash 

 with cold water, mix with more water under stiiTing, boil and 

 filter boiling hot. Boil again with water all that has been left 

 undissolved until the whole is either dissolved or the remnant 

 has been exhausted. The jNIalate of lead crystallises from the liquids, 

 when kept cold, and more of it is obtained by concentrating 

 the mother-ley. The whole of the Malate of lead is ground up 

 with water to a fine pulp, the latter is decomposed with sul])huret 

 of hydrogen, and the liquid is evaporated first with a gentle 

 heat and afterwards in a vacuum, when it will yield the pure acid 

 in crystalline needles, united to warty masses. — It is inodorous, 

 of a pure and strongly acid taste, deliquesces at the air, dissolves 

 most readily in water, alcohol and ether; the aqueous solution is 

 not clouded by lime-water either cold or hot. It fuses at 83" 

 and becomes decomjjosed in a higher temperature. Tlie Malates 

 dissolve nearly all in watex', most of them readily so. 



The quantitative estimation of Malic acid cannot be effected 

 through precipitation with metallic salts, because those Malates 

 ai-e either not insoluble in water or are decomposed during washing. 

 If the quantity of Malic acid has to be determined in a liquid 

 which contains no other acid, the solution is warmed with carbonate 

 of baryta, until the acid reaction has disappeared. It is then 

 filtered off from the excess of carbonate of baryta, is evaporated 

 to dryness and heated for some time at 100°; 100 parts of this 

 anhydrous Malate of baryta contains 43*09 parts acid. 



