208 Fjxperiments for ohtaining and 'preserving Potassium. 



als. The receiver which was used in the first experiment, is the 

 one described by M. Berzelius, a drawing of which may be seen 

 in the eleventh edition of Henry's Chemistry, also in the Elements 

 of Professor Silliman. It is composed of two cylindrical copper 

 vessels, the upper one, which is smallest, is inverted into the lower one 

 containing naphtha and in this the potassium is to be condensed. 

 A hole of a sufficient size to receive the tube of the retort, is made 

 in the upper portion of the receiver, also a small one for receiving a 

 bent glass tube dipping down into quicksilver as a safety tube to dis- 

 charge the uncondensed gases. 



First experiment with the receiver. 



The retort being placed in the furnace as seen in fig. 2. The fire 

 of charcoal was lighted and soon a mixture of carburetted hydrogen 

 and carbonic acid came over. A bent glass tube extending from the 

 end of the iron tube, and dipping into a cup of quicksilver below, 

 carried off the uncondensed gases. In about an hour the vapors of 

 potassium appeared in the tube, when it was immediately wiped out 

 clean and about a pound of naphtha was poured in the copper receiver 

 above mentioned, which was then fitted upon the iron tube. The gas 

 immediately made its appearance through the safety tube, and bub-' 

 bled through the quicksilver. At this stage of the process, the great 

 object is to keep up an uniform temperature ; for the bottle being at a 

 white heat or a very bright red, a slight variation either fuses the bot- 

 tle, or prevents the potassium from coming over. The latter effect 

 is produced even by throwing in fresh fuel ; so that unless the fire be 

 frequently fed by small charges of coal, the process is often checked. 

 That the operation is going on well is known by the constant evolu- 

 tion of gas ; if this be at any time suddenly stopped, it must proba- 

 bly arise either from the cooling of the retort, by throwing in fresh 

 fuel, or from the choking of the tube, or the fusing of the retort. 

 Whichever it may be, circumstances at the time will enable the 

 operator to determine. If the tube be choked for the first time, it 

 may be bored out by a suitable iron rod ; but if it be the second or third 

 time, we are generally obliged to throw down the grate and let the re- 

 tort cool. In about an hour and a half from the time the potassium ap- 

 peared distinctly in the tube, the latter was choked, when an iron rod 

 prepared for the purpose was passed through the opening in the re- 

 ceiver quite into the retort, when, the obstruction being removed, the 

 receiver was again attached to the tube. In fifteen minutes more the 



