282 
POTASSIUM AND SODIUM, 
or ferrocyanide from the compound termed " metal ;" nor 
does he claim the construction of apparatus wherewith the 
•process or processes may be carried on : but he describes 
some arrangements which have been found to answer. One 
of these consists of three iron air-tight covered pots, com- 
municating with one another in the manner of ordinary 
Woolfe's bottles ; that is to say, the induction-pipe of the 
first pot reaches to near its bottom — its eduction-pipe 
reaches down the interior of the second pot to near its bot- 
tom, and the eduction-pipe of this second pot terminates in 
like manner in the third pot ; while the eduction-pipe of the 
latter plunges beneath the surface of some water or other 
liquid, convenient for oxidising and arresting vapours of 
alkaline metal. Each of the pots has a man-hole in its 
cover. by[means of which it may be charged and discharged, 
and a door by which it may be perfectly closed. Each 
covered pot is so set in a furnace as to be heated to a tem- 
perature great enough to keep its contents in a state of con. 
stant fusion. Its charge, when fused, should about half fill 
it. By the use of this apparatus, the ammonia which is forced 
into the first pot, by reason of its own elasticity under the 
pressure attending its assumption of the gaseous state, passes 
through the fluid mixture of fused alkali and carbon in that 
pot, being there decomposed into nitrogen or cyanogen, and 
as cyanogen, combining with and saturating the alkaline 
metal present; after which, the ammonia or its nitrogen or un- 
combined cyanogen, which results from its action on the car- 
bon still remaining in that pot, passes into the second pot, to 
convert the alkaline metal, there present, into a cyanide. In 
like manner the ammonia or its nitrogen, or the resulting cya- 
nogen, may arrive in the third pot; then is the time for stop- 
ping the operation, in order that the -two first pots may be 
emptied and re-charged. Owing to the volatility of the al- 
kaline metals at high temperatures, the pipes of communi- 
cation between the pots are apt to become obstructed; for 
this reason they are proposed to be made straight, and joined 
