No matter how air-tight you keep it, the aroma evaporates or is absorbed.
Coffee can be ground and made as soon as cool; but it is better to let it stand for about twenty-four hours after being roasted.
If kept as air-tight as possible in a tin-box, it will keep very well for about a week.
Never buy ground coffee except when you cannot help it.
By taking a pinch of ground coffee and rolling it between wetted fingers, it will remain in grains, if pure; and will form in a ball if foreign matters are mixed with it.
TO ROAST.
In roasting, good coffee swells about thirty-three per cent., and loses about sixteen per cent. in weight.
Roast once a week or oftener.
Put coffee in the apparatus (cylinder, or drum, or roaster), the quantity to be according to the size of the roaster, or according to how much is needed. Have a rather slow fire at first; when the coffee has swollen, augment the fire, turning, shaking, tossing the roaster, sometimes fast, sometimes slowly, and take from the fire a little before it is roasted enough; the roasting will be finished before the coffee gets cold and before taking it from the roaster, which you continue turning and shaking as if it were yet on the fire.
A charcoal fire is the handiest, and more easily regulated.