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COOLING OF FLUIDS.

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structed upon the principles proposed to be employed, which will serve to explain thenature of this improvement. •

Let a be the source ofthe vapors, or the vessel,boiler, alembic, or closedpan that contains theliquid or sirup to be eva-porated or concentrated.The pipe b, through whichthe vapor passes as itrises in the boiler, is sur-rounded by another tubec,of larger diameter, closedat both ends. A pump d,draws from thereservoir e.warm water, which waterhas been heated by its pre-vious and continual pas-sage through the appa-ratus in contact with thesurface of the vapor pipes.

This pump forces the water by the pipe f, into the annular space or chamber between thepipes b and c, in which chamber, by its immediate contact with the pipe b, it acquires thetemperature of the vapors intended to be refrigerated. The pipe g conveys the water fromthe pipe c, into the annular colander or sieve H, which has a multitude of small holespierced through its under part, and whence the warm water descends in the form ofa continued shower of rain. To the end of the pipe b, a distiller’s worm i i, is connected,which is placed beneath the colander H. The entire length of the worm-pipe shouldbe bound round with linen or cotton cloth, as a conductor of the heat, which cloth willbe continually moistened by the rain in its descent from the colander. As this waterhas been heated in passing along the tube c, the shower of rain descending from thecolander will be at a higher temperature than that of the atmosphere, and, consequently,by heating the surrounding air as it descends, a considerable upward draft will beproduced through the coils of the worm-pipe.

If the colander and the worm-pipe are enclosed within a chimney or upright tube, asK K, open at top and bottom, a current of ascending air will be produced within it bythe descending shower of hot water, similar in effect to that which would be producedin a chimney communicating with a furnace, or to that of the burner of an arganalamp. Consequently, it will be perceived that in opposition to the descending rain, astrong upward current of air will blow through that part of the cylinder K x, which isbeneath the colander. When the air first enters the lower aperture of the chimney ortube x, it is of the same temperature and moisture as the external atmosphere ; but inits passage up the tube it meets with a warmer and damper atmosphere, caused by theheat given out from the hot fluid continually passing through the pipes, and by the hotshower of rain, and also by the steam evolved from the surfaces of the coils of the worm,which are continually wetted by the descending rain, the evaporation being considerablyaugmented by the cloth.bound round the worm-pipe, retaining the water as it descends indrops from coil to coil.

The atmosphere within the tube being of a higher temperature than without, acurrent of air constantly ascends and escapes at the upper aperture K, and its place issupplied by fresh air from the surrounding atmosphere, entering the tube below. Th efresh air thus admitted at the bottom of the tube, being cold and dry, will be suited totake up the heat and moisture within, because the water within the tube, being in astale of dispersion as rain, presents to the air many points, or a very extended surtace,ami also because it is of a higher temperature than the air; and, besides, cold dry air I scont inually renewed, and a source of warmth is furnished by the latent caloric to thesteam as fast as it is evolved. Thus a portion of the descending rain, or water, ievaporated, and the effect of this evaporation is to subtract caloric not only from thewater held in contact with the coils of the worm-pipe by the cloth enveloping it, b ut .from the hot vapors which pass through the worm. This process of evaporation na.,therefore, a cooling power, which is but slight in the lower part of the chimney or uK; because the temperature of the water, or rain, and of the worm, at this P ar *\ IS .i, ea lower temperature; but its refrigerating power increases as it rises town laScolander, and there it acquires its maximum of intensity, so that at any point be Vthe lower aperture of the cylinder and the colander, the current of air is always a icooler than the atmosphere of the region through which it passes (that is, at its mmum) ; and in passing this region of higher tenfperature, it is not only put in ec J

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