MISCELLANY 
On the preparation of Chloride of Potassa. By Professor Graham. — 
It is well known that the ordinary processes for this important salt are 
attended with some practical difficulties. When a stream of chlorine gas 
is passed through a strong solution of carbonate of potassa, the absorp- 
tion of the gas is rapid and complete, till one half of the alkaline carbo- 
nate is decomposed ; but the remaining portion, which is in a state of bi- 
carbonate, is not so easily acted upon. To decompose the latter salt com- 
pletely, chlorine must be applied in excess, and the decomposition is at- 
tended by the formation of free hypochlorous acid, as has been proved by 
M. Detmer. The liquid is also at the end highly bleaching, and contains 
much hypochlorite of potassa. The boiling necessary to convert the 
latter into chlorate of potassa and chloride of potassium, occasions, ac- 
cording to M. Morin, a considerable loss of oxygen, and thus lessens the 
product of the chlorate. When a strong solution of caustic potassa is 
substituted in this process for the carbonate, the absorption of chlorine 
proceeds without interruption ; but the liquid, when saturated, bleaches 
strongly from hypochlorite formed. A long-continued boiling is required 
to destroy this property completely, and as oxygen escapes, the chlorate 
obtained must be deficient in quantity in a correspondent proportion. The 
process which the author recommends, and which is attended by none of 
these inconveniences, consists in mixing carbonate of potassa intimately 
with an equivalent quantity of dry hydrate of lime, and exposing the 
mixture to chlorine gas. This mixture, although quite dry, absorbs the 
gas with prodigious energy ; the temperature rises much above 212°, and 
water is freely evolved. When saturated, it may be moderately heated, 
which destroys a mere trace of hypochlorite it contains. The whole lime 
is found in the state of carbonate, and the potassa in the state of ( chlorate 
of potassa and chloride of potassium. The solution of the two latter 
salts is neutral, without any bleaching property, and free from lime. The 
chlorate of potassa may be crystallized from it in the usual way. Car- 
bonate of potassa, when moistened and exposed to chlorine, without the 
hydrate of lime, absorbs the gas with great avidity, and certainly answers 
better than a strong solution of the same salts ; but the absorption becomes 
slow after the salt is iti the state of bicarbonate, and subsequently a large 
