CJiemical Science^:4^'' 413 



5. On MelliUc Acidy — Carbon, and Oxygen^ by MM. Wc^Icar wid 

 Liebeg. — iTliese pliilosophers have undertaken an analysis of DOiel- 

 litic acid, which they had been led to suspect, from its habitudes 

 when heated, to consist of carbon and oxygen only. The mellitate 

 of silver, for instance, when dry, gave no trace of water, or a hydro?- 

 genous product, by distillation, nor even when burnt by means of 

 oxide of copper. On further examination, it was found also to be 

 destitute of azote, for the gaseous products of its decomposition, by 

 oxide of copper, were totally absorbed by caustic potassa, 0.^36 

 grammes of mellitate of silver = 0.07058 of mellitic acid gave 66 

 cubical centimetres of carbonic acid gas, from which the compositioiji 

 may be calculated at 50.21 carbon, and 49.79 oxygen per cent. 

 Then calculating from the known equivalent number of mellitic a^jfii 

 (6^.3), the substance would appear to be composed of '^^ '' , 



''"■ ^: 4 atoms carbon . . . 3.05748 ''''^'"! 



^mvjbn^g ^ ^ 3.00000 ^^'t^s^ 



6.0574^"' '^^^ 



To test this result, the neutral mellitate of ammonia was deconil; 

 posed by oxide of copper, the last portions of gas from it were ^ 

 mixture of 4 volumes of carbonic acid, and 1 volume of nitrogen^ 

 which confirms the conclusion, tliat 4 atoms of carbon enter into thie 

 composition of 1 atom of the acid. t* 



On comparing the composition of mellitic acid with that o^ slic- 

 cinic acid, it appears that the only difference is, in the latter coii^ 

 taining hydrogen ; and that if the latter be theoretically abstracted,' 

 there remain the elements of mellitic acid in true proportions. It 

 is probable, therefore, that mellitic acid may be derived from the 

 decomposition of succinic acid, which, as we know, is often found 

 in fossil wood, although amber is wanting where the mellite is 

 found. 



Endeavours have been made to obtain mellitic acid by fusing and 

 subliming succinic acid in dry and moist chlorine, without, however," 

 obtaining any favourable result; the acid is not decomposed by 

 chlorine ; succinic acid, heated with caustic potash, disengaged 

 hydrogen, but produced only oxalic acid. ^ ^ 



Succinic acid was re-analyzed, but the results obtained agreea 

 with those of Berzelius. The succinic acid was first cleansed by 

 passing chlorine through its aqueous solution, until all its peculiar 

 smell was destroyed, and then purified by repeated crystalhzations. 

 It was obtained in perfectly white crystals, which were then sub- 

 limed in a mattrass by the heat of boiling sulphuric acid, and after- 

 wards decomposed. The composition obtained was, per cent., >q 

 Carbon . . . . 44.38 ^a 



Hydrogen . • . . ,«»vt;5.00 iili 



-nTjoibvtl /Oxygen o!iJ-^.'.'rr.. . ^,. \ .50.62 ji 



^« ,%ii:§ V i^ 'Jw'i S ■ . isoiif] 9iw^ 



it# A 3|uiv*i ^<»^^^.„ J _ V ^- , ^.100.001 iwd^^'rt sdi 



APRIL— JUNE, 1830. 2 E 



