Bi-Malate of Lime in the Berries of the Sumach. 295 



So abundant is the bi-malate of lime in the infusion of the berries 

 both of the R. glabmm and copallinum that when reduced by evap- 

 oration the whole liquid has the appearance of a thick light varnish 

 and is almost insoluble in alcohol, two characteristic properties of the 

 bi-malate. The process of Mr. Cozzens for preparing a pure malic 

 acid from these berries is therefore liable to the objection that by- 

 using alcohol as the solvent, the operator will lose all the malic acid 

 which exists in the bi-malate, and this I am inclined to think is nearly 

 all the malic acid of the infusion. From the very small portion of 

 acid matter which alcohol imbibes by standing for some time over 

 the inspissated infusion, it is obvious that little uncombined malic acid 

 can be present. In fact, nearly all the acid in the Rhus exists as a 

 bi-malate in combination with lime. In procuring malic acid from 

 the juice of the Sorbus in which it exists in an uncombined state, 

 the alcohol acts as a solvent of the acid, and is therefore employed 

 with advantage to separate it from mucilage and the other substances 

 with which it is mingled. But it is entirely inadmissible when the 

 acid is to be procured from the bi-malate of lime. 



The Bi-malate of Lime is readily procured from the berries in 

 considerable quantity and perfectly pure by the following process : 



A quantity of hot rain water or distilled water is poured over the 

 berries in a clean wooden or earthen vessel. After allowing the 

 berries to macerate for a day or two, the liquid is poured off and 

 evaporated carefully in an earthern or porcelain dish until it becomes 

 intensely acid. It is now filtered through animal charcoal or bone 

 black, repeatedly washed with muriatic acid. The liquid passes 

 through almost colorless having only a slight amber tint. If the 

 evaporation has been carried sufficiently far, a large deposit of crys- 

 tals will form in a few hours. The liquid being poured off and fur- 

 ther reduced by evaporation an additional crop of crystals may be 

 obtained and in this way nearly all the bi-malate may be separated. 

 The salt thus procured will often be slightly tinged with coloring 

 matter, in which case it should be re-dissolved in hot water and crys- 

 tallized anew. It is then perfectly pure. 



When the crystallization of the bi-malate has been rapid the mass 

 presents the pure and shining white of the sulphate of quinine. — 

 When more slowly conducted, hexagonal prisms of the most beauti- 

 ful proportions are obtained. The largest of these have generally 

 two of their parallel faces much broader than the rest, so that when 

 placed upon any smooth surface they have the appearance of rect- 



