230

METHODS OF OBTAINING POTASH.

fitted a glass tube, for the purpose of affording a passage to tireliquor as it filters through the sand.

Having arranged the apparatus iu this manner, take equal partsof quick-lime and potash of commerce, if the lime is very caus-tic; but in the contrary case, it requires twenty parts of limeto fifteen of potash : put water into an iron kettle, bring itnearly to a state of ebullition, and then add lime, which by itsslaking will bring the water to that state completely. When it isslaked mix the potash, and form of the whole a thick liquid,which must be suffered to cool a little. Then pour the mixtureinto the boxes, and immediately throw water over it; but toprevent the water from making holes, when added, place overit a small board, which will rise with the water.

Care must be taken to place earthen pans, or other vessels, toreceive the liquor which runs through the tubes; and, that theley may not absorb carbonic acid from the atmosphere, thevessels must be closed with care, in such a manner as to excludethe external air. It will be necessary also to keep water alwaysover the mixture, which must be collected till it passes tastelessfrom the tubes.

The liquors obtained are nearly of the same degree of strengthtill towards die end of the process; when they grow weak sud-denly.'

To evaporate the water, use should be made of cast-iron pots,beginning with the last portions, which are. a little weaker; andto prevent the necessity of keeping the strongest a long time incontact with the air when boiling, a strong ebullition is requisite.When the fluid is concentrated to a certain degree, any sulphateof potash that may be present will crystallize, and be preci-pitated.

To obtain dry potash, pour the concentrated liquor into a smallbason, and proceed with the evaporation, till a little of it pouredon an iron plate, or a marble slab, becomes solid.

Then put the concrete potash into a jar, and pour over it verystrong alcohol; die potash alone dissolves in it; the sulphate and