110 NUTRITIVE PLANTS, . 



such, in the grain, but which is formed in the process of roasting 

 it. By keeping the neck of the globular vessel cold, by means of 

 wet cloths, I found means to condense this aromatic substance, 

 together with a large portion of aqueous vapour with which it was 

 mixed. 



" The liquor which resulted from this condensation, which had 

 an acid taste, was very high flavoured, and as colourless as the 

 purest water ; but it stained the skin of a deep yellow colour, which 

 could not be removed by washing with soap and water ; and this 

 stain retained a strong smell of coffee several days. 



** I have made several unsuccessful attempts to preserve the fra- 

 grant aromatic matter which escapes from the coffee when it is 

 roasting, by transferring it to other substances. Perhaps others may 

 be more fortunate. But I must not suffer myself to be enticed 

 away from my subject by these interesting speculations. 



* If the coffee in powder is not well defended from the air, it 

 soon loses its flavour, and becomes of little value ; and the liquor 

 is never in so high perfection as when the coffee is made immedi- 

 ately after the grain has been roasted. 



" This is a fact well known to those who are accustomed to 

 drinking coffee, in countries where the use of it is not controled by 

 the laws; and if a government is seriously disposed to encourage the 

 general use of coffee, individuals must be permitted to roast it in 

 their own houses. 



" As the roasting aud grinding of coffee take up some considera- 

 ble time, and cannot always be done without inconvenience at the 

 moment when the coffee is wanted ; I contrived a box for keeping 

 the ground coffee, which I have found by several years' experience, 

 to preserve the coffee much better than any of the vessels commonly 

 used for that purpose. It is a cylindrical box made of strong tin, 

 four inches and a quarter in diameter, and five inches in height, 

 formed as accurately as possible within, to which a piston is so 

 adapted as to close it very exactly ; and, when pressed down into 

 it, to remain in the place where it is left, without being in danger 

 of being pushed upwards by the elasticity of the ground coffee 

 which it is destined to confine. 



" This piston is composed of a circular plate of very stout tin, 

 which is soldered to the lower part of an elastic hoop of tin, about 

 two inches wide, which is made to fit into the cylindrical box at 



