Of the Excellent Qualities of Coffee. 641 



japanned on the outside, provided the hoop to which it 

 is fixed below be made of copper ; but this hoop must 

 never be japanned nor painted, 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 is 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 em- 

 ployed 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 



VOL. IV. 



