ON VEGETABLE ASTRINGENTS. £>05 



In Aikin's chemical dictionary* we have an account of Galls not ho- 

 the great diversity, which exists in the structure and appear- mo o eneous - 

 ance of different gall-nuts, a circumfrance which appears 

 previously to have been but little attended to. I have found 

 my observations to correspond with those of the Mr. Aikins, 

 and to be fully confirmed by my experiments. Although 

 the same quantity of materials be employed, it is very sel- 

 dom that two infusions of galls are obtained of the same 

 strength, and T have found the difference amount to no less 'Infusions of" 

 than -Ir of the whole weight of the solid contents. In gene- one third of 

 ral, however, if finely powdered galls be infused in ten times thoi/ solid con- 

 their weight of boiling water for two hours, a fluid is pro- 

 cured containing T V of its weight of solid matter. An in- so iuble. 

 fusion of the same strength will generally be obtained, if the 

 powdered galls be macerated in ten times their weight of 

 cold water for 24 hours. If powdered galls be boiled or in- 

 fused in hot water, the fluid is commonly, though not al- 

 ways muddy, and does not become transparent, until it has Dec«ction or 

 been kept for some days, or even weeks, and a considerable not infusion, 

 part of its contents have separated from it, in the form of |f d aera y 

 mould or sediment. The muddiness is not removed by fil- e ren after 

 tering the fluid, and there is often considerable difficulty in filtration, 

 passing it through the common bibulous paper. This mud- 

 diness renders the warm infusions improper to beemployed 

 in experiments that require any great degree of delicacy. 

 If the galls be only coarsely powdered, warm water still Successive hot 

 produces an opake infusion, but if successive portions of infusions less 

 warm water be applied to the same galls, the infusions will ^ 

 gradually become less and less muddy, until after the 3d 

 or 4th they will be transparent ; but the period when the 

 muddiness ceases is not the same in all cases. It is probable, Somepartren- 

 that the muddiness in these mftarices does not depend upon b f[ e . in , so °" 

 any part of the galls which is originally insoluble, but upon heat. 

 some one of their constituents which is rendered so during 

 the process; for if a transparent infusion of galls be slowly 

 evaporated, and the residue be afterward digested in cold 

 water, a perfect solution of the whole can no longer be ob- 

 tained. Facts of this kind have been frequently noticed 



* Article, Gall-nut. 



