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 djstilling 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 the metal. - : 
From these facts, I 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 4s 
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 evely 
step of the operation, and keep up a regular and uniform heat ; there 
is also much danger of fusing the retort, from the cracking ope? 
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 fis 
operation, provided a few particulars, which I neglected to mention in 
