Notices respecting New Books. 63 



great quantity is suddenly volatilized each time the bottles are 

 opened, and from the instantaneous cold produced, the bottoms o-e- 

 nerally break and fall out : but if it be preserved in vessels iTke 

 those described, they may be of sufficient thinness to bear this sud- 

 den depression of temperature without fracture, and may even be 

 cooled previously with facility by a piece of ice and a little salt. 

 Sulphurous acid may be preserved in such tubes in small portions 

 for smgle experiments, or if in large quantity, it is casv to distil or 

 transfer it as has been described. When used for sulphurous acid, 

 they must of course be retained in a refrigerating mixture durinf^ 

 the distillation, they must be continued in this mixture whilst the 

 top piece is withdrawn, and also whilst the bend is given to them, if 

 that be required. It is also necessary that they be sealed when 

 thus cooled, for it cannot be done after they are exposed to the air. 

 The best method is to prepare the small aperture by drawing off 

 the extremity, to lift the tube into the air, then to apply the flame 

 of the lamp, which will not as yet seal it, and afterwards to lift up 

 the freezmg mixture, or depress the tube in it, still applying the 

 flame of the lamp : as the cold condenses the internal vapour the 

 current outwards will cease, and the extremity will close • instantly 

 withdraw the lamp so that the glass shall harden, and then the re- 

 ceiver may be taken out of the cold mixture, and preserved in a 

 glass or tumbler, in a place at ordinary temperature. Should there 

 be a doubt of the sealing being perfect, bring a little ammonia near 

 the extremity ; if no fumes are produced all is secure, if there be 

 fumes the same operation of sealing as that just described must be 

 resorted to. 



" Successive rectifications may be made in the same tube, by bend- 

 ing It with several angles as in the annexed figure ; such an appa- 

 ratus was found of great service in experiments upon the fluids ob- 

 tained by the compression of oil gas. The fluid is to be introduced 



/^ . — . . — ^ ^^ a 3t the open extremity a, so as to 



/\\ WVv n //\ J^ "^ '" ^^'^ ^"J'''^ ^' *''''" applying 

 ^ Vi> ^ W \7 a small blow-pipe flanle, thi 

 ^ f/ ^ }, glass should be softened at the 



neck, drawn out and sealed, the capillary termination at/being 

 open. On moderately heating b and cooling c, a distillation of the 

 more volatile part will fake place, the latter collecting at c : after a 

 time by keeping b and c warm and cooling d, a rectification of the 

 product at c may be effected, and this distillation may be again re- 

 peated upon tlie product at d by condensing in e. By forming 

 the angles of the tube as in the figure, the results may be returned 

 and redistilled ; for upon raising the end^ the product in c will first 

 return to b, then that in (/, and finally that in <? ; so that if the sub- 

 stance be sufficiently freed from the denser parts only after the 

 third or fourth distillation, the products in c and d may be returned 

 to b and redistilled as before, that in e being retained separate: 

 during such experiments e should be preserved very cold. 



" In experiments with the oil gas liquor, distillations of this kind 

 were oftcM to be performed in close vessels, that dissipation of the 

 more volatile parts might be prevented. In such cases after having 



introduced 



