210 Experiments for obtaining and preserving Potassium. 



tal was carried over into the receiver, it was evident that the expense 

 of the receiver and naphtha could be dispensed with altogether ; ac- 

 cordingly I performed all the succeeding experiments without them. 

 I will give a detail of one as recorded at the time in the Journal of 

 the Laboratory which is a pretty fair specimen of the others, except 

 that the proportions of the materials in the retort were varied till I 

 had ascertained that which was most successful. 



Experiment without the Receiver. 



The retort charged according to the preceding directions, was 

 placed in the furnace as before, with the tube open to the atmosphere. 

 At half past ten A. M. the fire was lighted ; at half past eleven the re- 

 tort was heated to a cherry red, as seen by looking through the tube. 

 Gas, chiefly carburetted hydrogen and carbonic acid, come over in 

 abundance. A quarter before twelve, gas was still constantly evolved, 

 but in smaller quantities, and the metal began to sublime over, as in- 

 dicated by the slight explosions which now commenced in the tube ; 

 this was immediately wiped out clean by a swab of tow on the end 

 of an iron rod and closed temporarily by a perforated cork, having a 

 bent glass tube dipping down into a cup of spirits of turpentine. 

 This arrangement was adopted instead of the safety tube and cup of 

 mercury, used in the former experiments. It now became desira- 

 ble to be able to look through the tube, and examine the progress 

 of the operation from time to time, without exposing the vapors to 

 the action of the air. For this purpose, 1 took a cork which fitted 

 the tube accurately, perforated it with a large hole, over one end fit- 

 ted a plate of transparent mica, and confined it in its place by means 

 of small tacks driven into the cork and made impermeable to gas 

 by cement of plaster of Paris. On the side of the cork which pro- 

 jected, a small round hole was made for receiving a bent glass tube, 

 dipping down into the cup of spirits of turpentine ; ihrough this the 

 gases were allowed to pass. My chief reason for using the spirits 

 of turpentine was its cheapness, the convenience of using it, and the 

 very slight action which it has on the vapors. The quicksilver is 

 soon covered with vapor of water, charcoal powder and various oth- 

 er foreign matters, which it is necessary to remove as fast as they 

 collect, while the oil of turpentine requires no watching, the surface 

 remains clear and even, and if the fluid should suddenly rush into 

 the tube, as occasionally happens, little or no damage would result from 



