C I T
CL A
( 294 )
parts of citric acid, mixed with fufficient waterboiling hot, diffolving 50 parts of the citrat oflime. b According to Vauquelin, 24 parts ofthe acid are faturated bp 18 of calcareous fpar.Hence 100 parts of the citrat of lime contain37.34 of lime, and 62.66 of acid. Prouftfound that 100 parts of the citrat wafhed anddried, left by calcination 31.5 of lime, andhence the remaining 68.5 mull be citric acidwith water in undetermined proportions. Dizefound that the acid required an equal weight ofpure chalk for faturation, hence (fuppofing thechalk to contain 53 per cent, of lime) 100 partsof the dry citrat perfectly free from extraneousmatter, will confift of about 65.4 of acid, and34.6 of earth. This fait kept under water in awarm place foon grows mouldy, the acid is de-compofed, and the water is covered with a cruftof carbonat of lime. Citrat of lime is decom-pofed by the oxalic acid, or the oxalat of pot-afli.
Metallic Citrats. Thefe have been but littleexamined. The acid dillblves zinc and ironreadily, and moll of the oxyds of the othermetals. It decompofes acetite of lead, as alreadymentioned, and the citrat of lead is infoluble inwater without an excefs of acid. Citrat of mer-cury is formed by adding this acid to the nitrator acetite of mercury. The fait is a flakey pre-cipitate of a brick-duft red.
The affinities of the citric acid appear to bein the following order.
Barytes, lime, potaffi, foda, ftrontian, mag-nelia, ammonia, and alumine. The compara-tive affinities of the metallic oxyds have not yetbeen determined.
CLARIFICATION is the feparation by che-mical means of any liquid from fubftances fuf-pended in it, and rendering it turbid. If a dif-ference can be made between clarification andfiltration , it is that the latter is effected by meremechanical means, but the former either by heator by certain additions, the ad ion of which maybe confidered as chiefly chemical. A few prac-tical obfervations belong to both thefe articles.
The liquors fubjected to clarification arealmoft without exception thofe animal or vege-table juices, in which the matter that rendersthem turbid is fo nearly of the fame fpecificgravity with the liquor itfelf that mere reft willnot effeft a feparation. In thefe too theliquid is generally rendered thicker than ufualby holding in folution much mucilage, whichfurther entangles the turbid matter, and pre-vents it from finking. Hence it is that vinousfermentation has fo powerful an effect as a cla-
* Dize.
rifier, (wine being much more limpid than thegrape or other fruit juice of which it is made)fince this procefs always implies the deftructionof a portion of faccharine mucilage, and theconfequent production of a thin limpid fpirit.
Coagulating fubftances are great clarifierswhen mixed with any turbid liquor, the procefsof coagulation entangling with it all mattersmerely fufpended and not diffolved, and carry-ing them either to the top in the form of a fcum,or to the bottom in the form of a thick fediment,according to circumftances. Thus to clarifymuddy cyder, the liquor is beaten up with afmall quantity of frelh bullock’s blood, and fuf-fered to Hand at reft for fome hours, afterwhich the liquor above is as clear as water, andalmoft as colourlefs, and at the bottom is a thicktough cake confiding of the coagulated bloodwhich has carried down with it all the opakematter fufpended in the liquor. Many otheralbuminous and gelatinous fubftances add in thefame manner. The effect of white of egg inthis way is known to every one. It fhould befirft mixed with the turbid liquor (a fyrup forexample) without heat and by agitation. After-wards on applying lefs than a boiling heat thealbumen of the egg coagulates, and carries upwith it all the opake particles of the fyrup,leaving the reft beautifully clear and limpid.
Sometimes clarification takes place in a very-unaccountable manner. Thus it is well knownthat a handful of marl or clay will clarify alarge ciftern of muddy water, and marl is alfoufed with advantage in clarifying vinous liquors.'
Mere heat will often clarify. Thus the ex-prefied juice of cabbage plants is a ftrong-fmelling, green, clammy, muddy liquid. Byheating, all the turbid matter feparates in theform of a green coagulum, and the liquor thatremains is almoft as limpid as water.
Clarification may often be detrimental. Inmany liquid medicines, fuch as decodlions ofmedicinal vegetables and the like, the medicinalportion refides chiefly in that part which ismerely fufpended, and therefore when feparatedby any kind of coagulation, the clear liquor isleft nearly inert. See Filtration.
CLAY. Than ; Germ. Argille, Fr.
Any natural earthy mixture which poffefiesplafticity and ductility, when kneaded up withwater, is in common language called a clay,which term is probably derived from the Latin glarea through the medium of the French glaife.All mineralogifts however have comprehendedwithin the appellation not only clays properlyfo called, but a few other mineral fubftances