COFFEE. 117" 



tne outside, provided the hoop to which it is fixed below be made 

 of copper ; but this hoop must never be japanned nor painted j and 

 it must always be made of sheet-copper or silver ; and the boiler 

 must always be heated over a small portable fire-place or lamp, 

 somewhat less in diameter above, than the hoop on which the boiler 

 is placed. 



" In order that the flat bottom of the boiler may not smother and 

 put out the fire, the brim of the small furnace or chafing-dish, which 

 is used, must have six projecting knobs at the upper part of it, each 

 about one quarter of an inch in height, on which the bottom of the 

 boiler may rest. 



" If these knobs (which may be the large heads of six nails) be 

 placed at equal distances from each other, the boiler will be well 

 supported ; and as the hot vapour from the fire will pass off freely 

 between them, the fire will burn well. As a very small fire is all 

 that can be wanted, no inconvenience whatever will arise from the 

 heating of the boiler on the table, in a dining-room or breakfast-room, 

 especially if a spirit lamp be used ; and the quantity of heat wanted 

 rs so very small, when the water is put boiling hot into the boiler, 

 that the expense for spirits of wine would not, in London, amount 

 to one penny a day, when coffee is made twice a day for four 

 persons. 



" It is a curious fact, but it is nevertheless most certain, that in 

 some cases, spirits of wine is cheaper, when employed as fuel, even 

 than wood. With a spirit lamp constructed on Argand's principle^ 

 but with a chimney made of thin sheet iron, which I caused to be 

 made about seven years ago, (and which has since become very com- 

 mon in Paris*,) I heated a sufficient quantity of cold water, to make 

 coffee for the breakfast of two persons, and kept the coffee boiling 

 hot, one hour after it was made, with as much spirits of wine as cost 

 two sous, or one penny English money," 



[Count Rumford. 



13 



