SS-Z Compositions and Preparations. Part III.

begin to drop, and the affusion of water is to be repeatedin the same manner, until three pounds have dropped,which will happen in the space of two or three days; thenmix the superior and inferior parts of the Jiquor togetherby agitation, and keep it in a well-stopt phial.

Liquor potass^e. Lond.Solution of Potass.Take of

Sub-carbonate of potass, one pound ;

Fresh lime, half a pound ;

Distilled water, boiling, a gallon.Dissolve the potass in two pints of the water ; add the rest of

the water to the lime. Mix the liquors while hot, set the

mixture aside in a covered vessel ; and after it has cooled,

filter it through cotton cloth.If any diluted acid, dropt into it, excite effervescence, more

lime must be added, and the filtration repeated.A pint of this liquor should weigh sixteen ounces.

Aqua kali caustici. Dub.Solution of Caustic Kali.Take of ^p

Fresh burnt lime, eight ounces;

Subcarbonate of kali, six ounces. ^^

Put the lime into an earthen vessel, and sprinkle uporfit ^Bpints of boiling water. With the slaked lime mix the sa^jand cover the vessel. Pour the mass, as soon as it hascooled, into a glass funnel, whose throat is obstructed witha rag. Having covered the funnel, let the ley drop into avessel placed below it, and pour water from time to timeinto the funnel, until three pints have passed through.Let the liquor be agitated, and kept in a bottle of green glass

well closed.If the ley be rightly prepared, it will have neither colour norsmell, and will scarcely effervesce when mixed with acids.If it effervesce considerably, add a little fresh burnt lime,in very fine powder; digest for twenty-four hours in a closevessel, with occasional agitation j then filter the ley in themanner already directed.The specific gravity of this liquor is to that of distilled wateras 1100 to 1000.

These processes do not differ materially. They are found-ed upon the affinity of lime being stronger than that of potass