178 Foreign and Miscellaneous Intelligence. 



important that has fyeen made for many years in pharmaceutical 

 chemistry*. 



13. PREPARATION AND COMPOSITION OF MALIC ACID. 



This curious vegetable acid has been obtained pure and crystallized 

 by M. Liebeg, and carefully analysed, for the purpose of setting the 

 discordant results of different chemists at rest. The expressed juice 

 of the ripe fruit of the mountain ash was boiled with animal char- 

 coal, which had previously been purified by muriatic acid ; and a 

 certain quantity of potash added, but so as to leave a great excess 

 of acid ; the whole evaporated till thick as syrup, then mixed with 

 five or six times its volume of spirit of wine, and the clear, vinous 

 liquor, after separation from the mucilaginous matter, distilled. The 

 thick viscid residue of the distillation was again acted upon by 

 alcohol, which entirely did away with the mucous state. Being 

 again distilled, the residue was diluted with much water, precipi- 

 tated by acetate of lead, and the malate of lead obtained, decom- 

 posed in water by sulphuretted hydrogen. The addition of potash 

 and treatment by alcohol has for its object the separation of tar- 

 taric acid and tartrate of potash, which occurs in the original juice, 

 and which otherwise would have given a mixture of tartaric acid 

 with the malic. As directed, the malic acid can contain only citric 

 acid, or traces of tartaric acid ; when concentrated, therefore, am- 

 monia is to be added in quantity insufficient to neutralize the liquor ; 

 alcohol, equal in volume to the liquid, is to be added also, and the 

 whole allowed to cool, when quadrangular crystals of the acid 

 malate of ammonia will be obtained, the salt being very little 

 soluble in alcohol, even though diluted. These dissolved in water, 

 precipitated by acetate of lead, and the precipitate decomposed by 

 sulphuretted hydrogen, yield pure malic acid ; which will be found 

 to crystallize by evaporation in the air, forming, first, acicular cry- 

 stals, and ultimately a solid crystalline mass. 



A crystallized malate of zinc was then formed, resembling in 

 properties that described by M. Braconnet. By a heat of 212 it 

 loses ten per cent, of water, without change of form ; at 248 it lost 

 other ten per cent., then becoming a white coherent powder. By 

 analysis, the salt gave 46.734 malic acid, 32.711 oxide of zinc, 

 20 . 555 water, the oxygen of the oxide, water and acid being as 

 1:3:4. Hence the equivalent of malic acid is 57 . 3, hydrogen 

 being unity. 



The malate of silver is anhydrous at 212, and composed of 

 66.975 malic acid, 33.026 oxide of silver per cent., which gives the 

 equivalent number of malic acid as 57.2. When the dry salt is 

 decomposed by heat, it blackens only for an instant, and yields 

 carbonic oxide gas, which burns like alcohol, and contains no 

 empyreumatic matter. 



* Ann. de Chiraie, xliii.,440. 



