Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/612

 TAR

Soluble Tartar. The procefs for making foluble Tartar, is this : Take of an alkaline fixed fait a pound, of water a gal- lon ; and having diflblved the fait in this water boiling, throw in cryftala of Tartar in powder as long as any fermentation is raifed, which ufually ceafes before thrice the weight of the alkali is thrown in. Then ftrain the liquor through paper ; and after due evaporation fet it by for the fait to cryftallize, or elfe evaporate the liquor wholly away, that the fait may be left dry.

This fait by the action of the alkali on the acid of Tartar, being freed from thofe grofs terreftrious parts, with which the cryftals of Tartar, how pure foever, remain ftill charged ; it duTolves readily, and keeps fufpended in cold water. Pe?n- berton's London Difpenfatory, p. 181. feq. The feveral alkaline falts, that of Tartar itfelf, the common pot-afhes, borax, t$c. all make a very good foluble Tartar ; and not only thefe but the common terreftrial alkali's, whether of the mineral kingdom as chalk or lime, or of the vegetable, as the afhes of plants after elixiviation ; or of the animal, as oyfter-fhells calcined or not calcined, and hartfhorn ; all thefe give a better or worfe foluble Tartar ; but of thefe none fuc- ceeds fo well as the oyfter-fhell, after it has been calcined ; the foluble Tartar prepared with this, cods alio greatly lefs, than when prepared with fait of Tartar, In wood-afhes there is always a part, which when mixed with water fwims, and is fufpended in it a long time, and at length fubfides into a kind of foft and impalpable matter ; and another part, which fubfides readily to the bottom, and feels _Tough and harm. It is the fiift of thefe fubftances alone, which being mixed with cream of Tartar, renders it foluble : The other part will not mix with the cream of Tartar, 01 produce any fuch effect, unlefs reduced to the nature of the firft, by repeated and violent calcinations, and then only a part becomes fo altered, the whole never is fo. It appears that the firft portion has been wholly diyefted of its acid by the fire, and thence is become fufceptibk of the impreffion of the weakeft acid, fuch as is that of the cream of Tartar j but in the fecond, or coarfer part, the acid it naturally con- tained remains fixed and concentrated, fo that, it is not fui ceptible of any impreffion from the weak acid of the cream ol Tartar. Mem. Acad. Par. 1733.

The different kinds of foluble Tartar have alfo their different degrees of folubiiity, or different readinefs to run into a liquor per deliquium. The moft eafily foluble of all others are thofe made with chalk, with lime, and with wood-afhes ; and that which is moft differently fo, is the kind made with borax; it will at length run however, and is truly foluble Tartar.

Regenerated Tartar. When cream of Tartar has been made foluble by any alkaline fubftance whatever, it may be revived or regenerated into cream of Tartar again ; its acid in this Itate has diffolved the alkaline matter presented to it, and that has been itfelf attenuated in fuch a manner as to render it capable of infinuating itfelf between the molecules or in- tegrant parts of the constituent matter of the cream of Tar- tar \ on this only depends the folubiiity of this preparation : and to render the whole of its primitive nature again, there re- quires no more than the addition of a new acid, which Ihall free the Tartar from this alkali ; but this muft neceflarily be ftronger than that naturally in the Tartar. Thus fpirit of ni- tre, or oil of vitriol, regenerate the fallible Tartar in a moment, as being more powerful acids than that in the cream of Tartar and therefore taking from it all its alkali's. It might be fuppofed alfo, that thefe being mineral acids, and that of the Tartar a vegetable one, they might therefore be the more proper to take up its alkali's ; but this is found not to be the cafe, for the acid of diftilled vinegar, which is not only a vegetable acid, but is alfo the very fame acid with that of Tartar, is alfo able to regenerate the foluble Tartars. It might feem wonderful that this fhould be able to effect this change without any fuperiority of force ; but it is to be ob- ferved, that in the cream of Tartar the acid has a terreftrial and alkaline bafis, which is natural to it in that form ; but in the ftate of foluble Tarter it takes a new alkaline bafis, which is not natural to it, but is fuch as the artift gives it ; and when we view the procefs in this light, it does not appear wonderful that an acid of its own kind fhould be able to take away from it this artificial alkaline bafis, though it was not able to take from it the natural one. Mem. Acad. Par. 173-1. This fecond or artificial bafis is different, according to the dif- ferent alkali's which have been employed to render the Tartar foluble, and confequently the fame acid may attach itfelf more to one than to another of thofe alkali's, and quit them the more or lefs eafily. There is one kind of foluble Tartar how- ever, which is not to be regenerated at all i this is that, which is made with borax.

Dr. Huxham fays, he as often experienced the good effects of regenerated Tartar in the cure of obstructions of the bowels, and for fluggifh humours. See the article Obstruc- tions of the Bowets.

3^pX * Lixivium. See the article Lixivium Tartan.

TARTARON, a fort of fine cloth or filk, mentioned in the flat. 4 Hen. VIII. c. 6. Blount, Cowel.

TARTARUM Tartarifatum, Tartaris'd Tartar, in chemiftry, ths name of a preparation of Tartar; the manner of doing

TAR

which is given by Boerhaave, and is as follows : Reduce Come of the pureft white Tartar to powder, and boil this pow- der in ten times its weight of water in a large copper veffel, till it appears petfeQIy diflblved ; let it after this continue boil- ing till the liquor become tolerably tranlparent, and of an acid tafte ; then drop into it from on high oil of Tartar fir ddi- quium, the liquor being ftill kept boiling ; upon the falling in of eacli drop there arifts a great ebullition, uccalioned by tire meeting of the acid and alkali. Large bubbles appear on this, and in thefe the chemifts have imagined they found the figures of clutters of grapes.

The operation is to be patiently continued till there is no more effervefcence made by the hilling in of the drops of the oil. The acidity of the Tartar will be then fo perfectly fatu- rated with its own alkali, that it will appear neither acid nor alkaline, but a third fait ; great caution hovaevcr mud be ufed in oblerving the true point of faturation, otherwife the fair, will be when nnilhed either a little acid, or a little alkaline, as the one or the other exceeds.

The liquor is then to be ftrained feveral times through a flannel, till perfectly dear ; it is of a deep brownifh cokiur, and brackifh faline tafte, but has no fcent. If this be evapo- rated to a pellicle, and fet to cryftallize, it forms a fait which is a Tartar, eafily foluble in water, even when cold ; and \* very properly to be called foluble Tartar. Hoerhaav. Chem. Part 2. p. i6r.

Vitnalatei Tartar, Tartarum Vitrlolattm. The chemifts have fomerimes boafted of great virtues, in what they call the magiftery of this fait; this is the earth precipitated in the making of it. It is the opinion of fome ingenious au- thors, that all fixed falts are produced by a blending together of the acid and alkaline falts, which the plants they are ob- tained from originally contained, with fome earth, 'f 'he mak- ing of this preparation of Tartar and vitriol, gives great ftrength to his opinion by means of this magiftery j which (hews, that an earth nectliary to the cementing a mixture of an acid and an alkali into a neutral fait, may exift even in one of the principles thcmfelves, though unfeen by us ; and that, as in the prefent inftance, in fo large a quantity, as not only to be fufficient for the combining the two volatile fubftances into a fixed one, but even to leave a renfcinder of it that was not neceflary.

While the acid of vitriol is poured upon the diflblved fait of Tartar, or its oil per deliquium, for the making of this fait, during the great effervefcence between the acid and the alkali' there is a precipitation made of an earth, for the feparation of all which great care is to be had to the degtce of faturation of the alkali with the acid. This earth afterwards may be fe- vered by filtration. This earth is precipitated not out of the fpint ot vitriol, but out of the fait of Tartar; and this expe- riment (hews, that this fixed fait did originally contain that earth, which, according to the fyftem of the formation of fixed falts out of volatile ones originally rending in plants, muft neceflarily be mixed with them, and which not being able to mix with the acid, is feparated and thrown off in trie conflict, in which the acid mixes itfelf with the reft. This earth is what is pompoufly called the magiftery of vi- triolated Tartar ; but it is very wrong to give that name to an earth, which has none of the properties of that or any other fait ; and they greatly deceive themfelves and their patients who prefcribe it inftead of the fait itfelf. Its faline tafte pro- bably has induced them to think, that it poffefled great vir- tues ; but this is not innate, but adventitious, and the effect only of the fluid in which it was precipitated : It cannot buD have fome of the falts of that fluid hanging about it, when firft made ; but thefe may, by repeated warnings, be carried wholly off, and the magiftery will then remain a pure fimple earth, and (hew itfelf to be no other than that earth which may be properly called the earth of all fixed falts ; and which, though neceflary to give the fait of Tartar its form as a lixi- vial (alt, yet being not neceflary to it in its new form of a neutral fait, is depofited in the making it into that form. It yet remains to be proved by more numerous experiments^ that the fixed falts of plants owe that form only to a fixine earth, combining their two original volatile principles into a fixed mafs ; for if this be truly the cafe, there then needs no more to the volatilizing them again, but the diveftins them of this earth. Phil. Tranf. N°. 92.

TARTAREAN, a word ufed by fome authors to exprefs fpi- rit of tartar. * r

TARTARUGA, in zoology, a name by which the Portuguefe in America call a fpecies of tortoife, known among authors by its Brafihan name jurucua. See the articles Jurucua and Testudo.

TARTI Lapis, a (lone mentioned by Ludovicus Dulcis, and fome other authors, and laid to be very beautiful, having all the colours of the tail of a peacock, and to have many medi- cinal virtues. It was probably fome fpecies of agate j but the (hort account given of it will not enable us to guefs what oar- ticularkind. r

TARTON Rain, in botany, a name ufed by fome authors for the heath (purge, or that fpecies of the thymelsea which is cal- led jannamunda in the catalogues of the materia medica. Park

Theat.

p. 199.

TARUM,