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



angles, slightly beveled at the edges. In the salt suddenly crystal- 

 lized the crystals are much more slender, and are perfectly regular 

 hexagonal prisms with beveled extremities. They are frequently in 

 pairs crossing at right angles, and in groups formed of several of 

 these pairs. The variety of proportions among the different crystals 

 and the exact symmetry which each presents are matters of very 

 pleasing observation through the microscope. The great facility 

 with V. hich this salt crystallizes from the infusion of the berries, led 

 me at first to doubt whether the acid contained in it was really the 

 malic, for it would appear from the remarks of Berzelius and Thom- 

 son on the bi-malate that hitherto it had not been procured in the 

 crystalline form from the juices or infusions of plants. The former 

 chemist in the fourth volume of the Traite de Chimie, speaking of 

 this salt under the title of Sur-malate Calcique observes, "Ilressem- 

 ble a la gomme parson aspect," and again, "Ce qui vient d'etre dit 

 ne se rapporte qu'au sel tire des plantes ; d'apres Braconnot celui 

 qu'on prepare a I'aide de I'acide, cristallise en prismes hexagones." 

 Dr. Thomson does not speak of it as crystalline and states that 

 " when the supermalate of lime is evaporated to dryness it assumes 

 exactly the appearance of gum arabic." 



A very careful examination of the crystalline salt shows it to be a 

 true bi-malate and I am therefore disposed to think that the uncrys- 

 tallizable character of the bi-malate procured from the Sorbus, Sem- 

 pervivum, he. arises from the admixture of mucilage and other im- 

 purities. 



The salt procured as above is intensely but agreeably acid. It 

 dissolves abundantly in water but in very small proportion in alcohol. 

 At a low heat it fuses and parts with its water of crystallization, as- 

 suming at the same time a gummy aspect. A little below redness 

 the acid is decomposed, the mass swells very much, and if the heat 

 be increased, every thing is driven off but the lime which remains in a 

 bulky form, perfectly pure and white. A single crystal placed on 

 a slip of platinum foil and held over a spirit lamp presents a very cu- 

 rious appearance, first melting and in a moment after shooting up in 

 a white column of pure lime. This phenomenon is quite character- 

 istic of the salt. 



In Investigating the nature of this salt of which as already stated 

 I at first entertained some doubts, I made the following experiments. 



1. A portion of the salt was heated to bright redness in a plati- 

 num capsule so as to drive off all the water and acid. The white 



