68 Transactions of the 



Tlie tree does npt thrive well in rich ground ; it likes a western 

 exposure and loose gravelly soil, where it may often get showers 

 of rain. When the berries are ripe they are pulled from the trees 

 and transferred to a machine called the ' pulper,' by which the 

 outer pulp is removed. The seeds are then soaked in water to 

 remove all mucilaginous matter, and, after they have been care- 

 fully dried, the parchment-like skin in which they are wrapped is 

 removed by a winnowing machine. In Brazil, however, the berries 

 are gathered from the trees, and-allowed to dry without the fleshy 

 part being removed. They are, when dry, put into a mill which 

 crushes the husks, and allows the seeds to be separated. By this 

 method the coffee is said to have a finer flavour. 



Before being used for making our well-known beverage, the 

 coffee seeds undergo the process called ' roasting.' Here the 

 coffee loses in weight, though it gains in bulk, and it assumes a 

 colour more or less dark, according to the amount and duration 

 of the heat applied. 



The raw coffee-bean contains nearly : — 



34 parts per cent, cellulose. 



15 „ sugar. 



13 „ fat. 



12 ,, water. 



10 „ casein. 



3 ,, nitrogenous substances. . 



3 „ oil. 



6 „ ash. 



3 „ other matter. 



8 ,, caffeine (tbeine). 



The last-named substance is found in tea also, and it separates 

 from its solutions in silky needle-shaped crystals, which have a 

 slightly bitter taste, melt at 178° C. (352° Fahr.), and sublime 

 without decomposition at a higher temperature. Their composition 

 is CjHioNiO. + HjO. This caffeine, or theine, is a weak base which 

 forms salts with acids. It exists in different proportions in differ- 

 ent kinds of coffees. The coffee most generally consumed in this 

 countiy contains from a quarter of a pound to a pound in the 

 hundred. By boiling a mixture of coffee and slaked lime in the 

 proportions of tvi^o of coffee to one of lime, half a per cent, of theine 

 may be extracted. Taking equal weights of tea and coffee, tea 

 yields about twice as much theine as coffee does, but as we gene- 

 rally use a much greater weight of coft'ee than of tea, a cup of 

 coffee will contain as much theine as a cup of tea; while in 

 France, where the tea is usually weak and the coffee strong, a 

 cup of coffee will contain nearly twice as much caffeine as a cup 

 of tea does. 



