484 Miscellaneous Intelligence, 



dissipated ; the solution was filtered and left to crystallize. The 

 pure crystals, being dissolved in water, were precipitated by acetate 

 of lead, and the mellitate of lead, after being well washed was de- 

 composed by sulphuretted hydrogen; being filtered, the solution was 

 evaporated to dryness, during which the mellitic acid precipitated 

 as a white powder; being dissolved in cold alcohol, and left to 

 evaporate spontaneously, the acid was obtained in acicular ciystals. 

 In this state it is very acid, unaltered by air, very soluble in water 

 and alcohol, and sustains a considerable heat without change ; it 

 does not fuze, but ultimately sublimes, though probably not without 

 decomposition. When boiled for a considerable time with alcohol, 

 it undergoes a peculiar change, and occasions the production of a 

 new acid substance, resembling the benzoic acid. 



33. On a New Acid existing in Iceland Moss. — The reddish 

 purple colour which is produced by adding a decoction of Iceland 

 moss to per-salts of iron, has been attributed to the presence of 

 gallic acid, but is found by M. Pfaff to be occasioned by a new acid 

 body which may be separated in the following manner. A pound 

 of the lichen cut small is to be macerated in solution of carbonate 

 of potassa, until all that is soluble is separated; the above quantity 

 will neutralize two gros* of the carbonate. The filtered liquor is 

 to be precipitated by acetate of lead, and the brown precipitate 

 produced, when well washed, is to be diffused through water, and 

 sulphuretted hydrogen passed through it until all the lead is sepa- 

 rated. The filtered liquor is acid, and by spontaneous evaporation, 

 yields dendritic crystals. The crystals, when heated, carbonize, 

 but produce no odour like that of tartaric acid, and lime is left. 

 If they be dissolved and acted upon by alkaline carbonates, car- 

 bonate of lime is thrown down, and alkaline salts, containing the 

 new acid, are produced. 



The potash salt crystallizes in quadrilateral prisms, needles or 

 plates, and is not deliquescent. The soda salt has similar charac- 

 ters, and the ammonia salt crystallizes in needles. These salts 

 abundantly precipitate the acetate and muriate of iron of a red 

 brown colour; they precipitate sulphate and nitrate of zinc white ; 

 muriate of manganese slightly of a clear brown colour ; barytic and 

 strontian salts abundantly white ; being mixed with strong solutions 

 of muriate or acetate of lirae, they gradually produce an acicular 

 crystalline white precipitate ; acetate of silver yields an abundant 

 white precipitate, which does not change colour in less than 

 twenty-four hours : they do not precipitate salts of glucina, mag- 

 nesia, alumine, uranium, nickel, copper, cobalt, gold or platina. 

 This substance has been named the lichenic acid, and is dis- 

 tinguished from boletic acid by the different character of its va- 

 pour, and by forming an insoluble salt with baryta. — Bull. Univ. 

 A. viii. 270. 



34. Bemarks on the Preparation ofM. Gautier^s Ferro'prussiate 



* About one hundred and twenty grains. 



