62 Processes for Potassium. 



At this temperature, however, the green vapor began to be seen by 

 looking through the tube. I kept up the heat regularly and uniformly 

 for nearly three hours, during the whole of which time, the vapor of 

 the metal could be seen in the retort, but, to my great surprise, did not 

 obtain ten grains of potassium. I attributed my failure, in this case, 

 to the possibility that there might have been but little potassium in the 

 receiver, though the operation had been, apparently, a successful 

 one. To ascertain whether this was probably the case, I repeated 

 the operation of distilling and redistilling three successive times, with 

 fresh materials. In each distillation were used twelve ounces of 

 potassa, and the redistillations performed as above described, but in 

 no case did I obtain a drachm of the metal. In the last of the above 

 experiments, after giving up the case as hopeless, I removed the 

 receiver from the fire, let it cool, and filled it with naphtha, after 

 which I detached its contents by means of the iron scraper, and 

 finding they contained some potassium, I coated the receiver again, 

 replaced it in the furnace, and obtained, at a full red heat, nearly a 

 drachm and a half of die metal. 



From these facts, 1 think we are justified in concluding that the 

 redistillation, or purification of potassium is not successfully perform- 

 ed without first detaching it from the receiver; which circumstance 

 seems to facilitate the operation much in the same manner as 

 minute mechanical division affects some other chemical changes. 

 Hence the chief advantages of this receiver are, that It enables us 

 to continue the process, without interruption, for an unlimited time, 

 or until no potassa remains in the retort ; and secondly. It may be 

 used for redistillation of the product after It has been detached ; the 

 operation is much more successful when the materials (after being 

 wet with naphtha) have been previously broken into small fragments, 

 which is easily done by means of a clean Iron mortar. 



I have not yet attempted to ascertain the largest quantity of metal 

 which can be procured at a single operation with this apparatus, but 

 am confident, that, by careful management, two ounces are not too 

 high an estimate. Yet It must be remembered that much depends 

 on the practical skill of the operator ; he must watch narrowly every 

 step of the operation, and keep up a regular and uniform heat; there 

 is also much danger of fusing the retort, from the cracking open, or 

 fusing of the lute which covers it ; hence It is necessary to have good 

 clay, to dry it very moderately, and to use much caution In luting. 

 The redistillation is performed with much less difficulty than the first 

 operation, provided a few particulars, which I neglected to mendon in 



