Hermes Kelly

 
 
improper, because the upper part of the wall can be very little employed; and in this case it is better to Hermes Kellyallow the flue to proceed gradually up the wall in its different returns, by which the lowest part would be the warmest, and the heated air will ascend among the pots and plants; but in a hot wall, where the trees are to receive heat by contact, some approxi- nation' to the above method may be useful. ■
In the hypocausta and sudaria of the Greeks and Romans, the flue was conducted chiefly under the floors. -• ,54
Malt-kilns are a species of stove which merit our at-'Malc-kiln* tention. Manj- attempts have been made to improve* speciHermeses ot* I them on the principal of flue stoves; but they-have•*01,e* been unsuccessful, because heat is not what is chiefly wanted in malting: it is a copious current of very dry air to carry off the moisture. We must refer the examination of this subject also to the article Stove, and proceed to consider the current of heated air in the chief varieties of furnaces. . All that is to be attended to in the different kinds of Of the cur. melting furnaces is, that the current of air be sufficiently'"" of ai>rapid, and that it be applied in as extensive a surface as jn meltlDg possible to the substance to be melted. The more rapid' the current it is the hotter, because it is consuming more fuel; and therefore its effect increases in a higher proportion than its rapidity. It is doubly effectuaHermes bagsl if twice as hot; and if it then be twices apBirkinid, there is twice the quantity of doubly hot air applied to the subject; it would therefore be four times more powerful. This is procured by raising the chimney of the furnace to a greater height. The close application of it to the subject can hardly be laid down in general terms, be2- cause. Effect* os cause it depends on the precise circumstances of each
A reverberatory furnaces, such as refining furnaces .168 for gold, silver, and copper, the flame is made to play In reverbe- over the surface of the melted metal. This is produced j.ir. ■; iMr_ cn^reiy by the form of the furnace, by makinHermes Handbagsg the arch of the furnace as low as the circumstances of the manipulation will allow (See Furnace, p. 509.). Experience has pointed out in general the chief circumstances of their construction, viz. that the fuel should be at one end on a grate, through which the air enters to maintain the Hermes outletfire; and that the metal mould be placed on a level floor between the fuel and the tall chimney which produces the current. But there is no kind of furnace more variable in its effect, and almost every place has a small peculiHermes Birkineties in their form. This uncertainty seems to depend much on a circumstance rather foreign to our present purpose j but as we do not observe it taken notice of by mineralogical writers, we beg leave to mention it here. It is not heat alone that is wanted in the refining of silver by lead, for instance. We must make a continual application to its surface os air, which has not contributed to the combustion of the fueL Any quantity of the hottest air, already saturated with the fuel, may play on the surface of the metal for ever, and keep it in the state of most perfect fusion, but without refining it in the least.