COFFEE. Ill 



exactly as possible, and so as not to be moved up and down in it 

 without employing a considerable force. This hoop is rendered 

 elastic, by means of a number of vertical slits made in the sides 

 of it. 



On the upper side of the circular plate of tin, which closes this 

 hoop below, and in the centre of it, there is fixed a strong ring, of 

 about one inch in diameter, which serves instead of a piston rod, or 

 a handle for the piston. The cylindrical box is closed above by a 

 cover, which is fitted to it with care, in order that the air which is 

 shut up within the box (between the piston and the cover) might 

 be well coufined.' , 



" Boiling-hot water extracts from coffee, which has been pro- 

 perly roasted and ground, an aromatic substance of an exquisite 

 flavour, together with a considerable quantity of astringent matter, 

 of a bitter but very agreeable taste ; but this aromatic substance, 

 which is supposed to be an oil, is extremely volatile, and is so fee- 

 bly united to the water that it escapes from it into the air with great 

 facility. If a cup of the very best coffee, prepared in the highest 

 perfection, and boiling hot, be placed on a table, in the middle of a 

 large room,'and suffered to cool, it will in cooliug fill the room with 

 its fragrance; but the coffee, after having become cold, will be found 

 to have lost a great deal of its flavour. If it be again heated, its 

 taste and flavour will be still further impaired ; and after it has been 

 heated and cooled two or three times, it will be found to be quite 

 vapid and disgusting. The fragrance diffused through the air is a 

 sure indication that the coffee has lost some of its most volatile 

 parts ; and as that liquor is found to have lost its peculiar flavour, 

 and also its exhilarating quality, there can be no doubt but that both 

 these depend on the preservation of those volatile particles which 

 ecape into the air with such facility." 



M In order that coffee 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 

 temperature, either during the time employed in preparing it ; or 

 afterwards, till it is served up. 



w This may be done by pouring boiling water on the coffee in 

 powder; and surrounding the machine in which the coffee is made, 

 by boiling water; or by the steam of boiling water : for the tern- 



