76 THE SUCCINIC ACID GROUP. 



lesser quantity in all fermented fluids, and it is possible that 

 it is formed from glucose, together with mannite (C 12 H 12 O 12 = 

 C 8 H 9 O 8 + C 4 H 2 O 3 .HO, Liebig).* This acid is usually obtained 

 by the distillation of amber, to which a little sulphuric acid has 

 been added ; the sublimate is then purified by boiling with nitric 

 acid. 



Tests. As this acid exhibits no very characteristic reactions 

 towards other bodies, we can only determine its presence by 

 separating it in a state of purity and then analysing it. 



SEBACIC ACID. C 10 H 8 O 3 .HO. 



Properties. This acid (known also as pyroleic acid) is. in its 

 external appearance, very similar to benzoic acid, forming white, 

 nacreous, acicular crystals, grouped together in loose heaps : the 

 microscope, however, readily reveals the difference in the external 

 characters of these two acids. It forms either whorled clusters, 

 similar to margaric acid, or large plates extending from a centre, 

 and intersecting one another at various angles, which run into sharp 

 points, without forming an angle capable of measurement ; in their 

 mode of grouping, these crystals most closely resemble well-formed 

 crystals of margaric acid ; the individual crystalline leaflets are, how- 

 ever, far greater. This acid fuses at 127, without losing its basic 

 water, into a colourless oil, which, on cooling, solidifies into a 

 crystalline mass ; at a higher temperature it sublimes undecom- 

 posed ; it is only slightly soluble in cold water, but in hot water 

 as well as in alcohol and ether, it dissolves readily; it has a 

 pungent rather than an acid taste, and reddens litmus. By pro- 

 longed boiling with nitric acid of 1*4 specific gravity, it is gradually 

 (in six or eight days) converted into pyrotartaric acid. (C. 

 Schlieper.)f 



Composition. According to the above formula it consists of- 

 Carbon 10 atoms .... 59-406 



Hydrogen .... 8 .... 7*921 



Oxygen 3 .... 23'762 



Water 1 .... 8-911 



100*000 

 The atomic weight of the hypothetical anhydrous acidm 



* Handwbrterbuch der Chemie, von Liebig, Wohler, u. Poggendorff. Bd. 3, S. 124. 

 t Ann. d. Ch. u. Pharm. Bd. 70, S. 121-129. 



