626 Of the Excellent Qualities of Coffee. 



perature, containing a small quantity of the powdered 

 amber intimately mixed with it, on exposing these 

 two glass vessels with their contents to cool in the 

 air in a quiet room, no motion will be perceived among 

 the particles of the pure brine (which are invisible), 

 but the motions which will be seen to take place among 

 the particles of amber in the other tumbler will af- 

 ford a convincing proof that the apparent rest in the 

 pure brine must necessarily be a deception, and that 

 the particles of both these masses of cooling liquid 

 are most undoubtedly in motion. 



As soon as these liquids have acquired the tempera- 

 ture of the surrounding atmosphere, their internal mo- 

 tions will cease, but on every change of temperature 

 they will recommence. 



We may conceive the particles of amber dissem- 

 inated in the brine to represent the particles of the 

 aromatic substance disseminated in new-made coffee : 

 as long as the coffee remains at rest, — that is to say, 

 as long as its temperature remains unchanged, — these 

 aromatic particles cannot escape, for they cannot come 

 to the surface of the liquid, but when the liquid is put 

 in motion their escape is greatly facilitated. 



When the cause of any evil is perfectly known, it is 

 seldom very difficult to find means to prevent it. 



In order that coflFee may retain all those aromatic 

 particles which give to that beverage its excellent 

 qualities, nothing more is necessary than to prevent all 

 internal motions among the particles of that liquid, by 

 preventing its being exposed to any change of temper- 

 ature, either during the time employed in preparing it, 

 or afterwards till it is served up. 



This may be done by pouring boiling water on the 



