THE BEGINNINGS OF LIFE. 



439 



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^ Each liquid was placed in a glass tube about three- 

 quarters of an inch in diameter, nine inches long, and 

 closed at one end by fusion of the glass. The open end 

 of the tube was then drawn out so as to form a thick 

 capillary tube, which was afterwards connected with a 

 SprengePs mercurial pump. The action of the pump 

 soon produced a tolerably good vacuum, when on gently 

 warming the liquid, the latter began to boil, its vapour 

 expelling the last traces of air from the apparatus. 

 After the boiling had been continued for several 

 minutes, the tube was hermetically sealed at the capil- 



lary part. 



«The tubes were now placed in the wrought iron 

 digester, described by me in the Philosophical Trans- 

 actions for 1854, p. 260. It consists essentially of a 

 cylindrical iron vessel, with a tightly-fitting cover, 

 which can be securely screwed on to it. Through the 

 centre of the cover passes an iron tube, which descends 

 half way down the centre of the cylinder. This tube 

 is closed at bottom, and contains a column of mercury 

 about an inch long^ and a thermometer plunged into 

 the mercury shows the temperature of the liquid inside 

 the digester. 



'Water being now poured into the digester until 

 it covered the tubes^ and the cover having been 

 screwed on^ heat was applied by means of a gas 

 stove. 



' The temperature was allowed to rise to about 

 150° C, and was maintained between 146° and I53''C 



