Notices respecting Neiv Books. 



61 



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other means. If the distillation be unsatisfactory, it is easy to re- 

 turn the product and repeat the operation ; if satisfactory, then 

 by applying a tile at c the tube is readily divided, and the rec- 

 tified portion obtained in the closed part, constituting a separate 

 vessel. 



" Distillation is frequently performed in a tube-apparatus, pre- 

 cisely similar to the ordinary retort and receiver. A piece of tube 

 sealed at ope end, and then bent as in the figure, forms what is called 

 a tube-retort. Fluid substances are easily 

 introduced into it through a little tube fun- 

 nel, made by heating the middle of a piece 

 of tube about two inches long, and half an inch in diameter, by the 

 lamp, and then drawing it out into a capillary tube and separating 

 it of a proper length. A receiver for such a retort is made of a 

 piece of straight tube of larger diameter closed at one end. The 

 beak, of the tube-retort is merely inserted an inch or more into the 

 tube-receiver, the junction is left open, and the latter is cooled, if re- 

 quired, in any of the usual ways. Occasionally 

 it is advantageous to draw out the beak of the 

 retort into a capillary form, as has been before 

 described ; it will then enter into vessels hav- 

 ing small apertures and necks. Sometimes it 

 is very useful to contract the necks of tube- 

 receivers in a similar manner, as will hereafter 

 be more evident. 

 " When a larger tube-retort is made use of, it is often useful to 

 draw out and contract the neck, for the 

 purpose of diminishing its capacity, and 

 consequently the quantity of vapour which 

 it can contain ; a common narrow-necked 

 phial then makes an excellent receiver. 

 The tube-receiver is frequently varied in form with advantage, by 

 making it of a bent piece of tube open at both ends, and when one 

 end of it is formed as at b in the following 

 figure, it is exceedingly convenient for 

 pouring out minute portions of the liquid 

 contained in it without waste ; for by 

 bringing the small extremity b against a 

 glass rod or a plate, and inclining the re- 

 ceiver, as little or as much of the fluid may 

 be delivered as is required. 

 " These tubular vessels may be supported with facility, some- 

 times upon the tabic across two or three pieces of glass tube, or 

 rod, or upon bent rings, or in the air upon the edges of glasses 

 placed side by side, or upon retort stands. The arrangements are 

 80 simple tha't no difficulty can occur with respect to them. The 

 receivers may be cooled by wet paper, or by placing them in wa- 

 ter in a glass or Wedgwood's dish, or by putting them into a hole 

 in a piece of ice, into which a little salt may be occasionally intro- 

 duced. 



" In cases of distillation upon a small scale, where, besides a fluid 



product, 



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