VEGETABLE POWDERS 



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Fig. 39. Asafoetida. Characteristic appearance of water mounts, a, 

 a bit of the gum from which numerous minute globules are thrown off into the 

 surrounding water, showing very active Brownian movement; b, irregular globules 

 of the gum; c, globules of the gum as they appear in a heated mount. The larger 

 globules gradually take up (by positive surface tension and adsorption) the smaller 

 particles. Some remain clear by virtue of not taking up particles. Gradually 

 the globules become agglutinated and massed; d, bast cells, the most constantly 

 present impurity in even the best quality. 



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