Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/408

 SAL

Ghuher's Salt. See Sal mirah'de, fupr. Salts if Count Lagarais, a name by which the trench and Come other nations call a preparation of vegetable bodies, invented by the gentleman whofe name it bears, but very improperly called by him a fait.

The hiftory of thefe preparations is this : in the year 1731, the Count de Lagarais mewed the French king tome pow- ders, which he proved to be very ufeful in medicine, and which he called the effential falts of cerium plants. 1 he me- thod of making thefe was long kept a fecret, but at length the difcoverer publifhing it to the world, it appeared that they were made by means of water only, agitated in a vio- lent and continued manner in a clofe veflcl with an inftru- ■ ment rcfembling a chocolate mill. Mr. Langelot had be- fore attempted a refolution of this kind of vegetable, and other fubftances, by means of water and motion, but his was done by grinding them with a very fmall quantity of water at a time ; whereas this of the Count's is by pow- derino- the ingredients, mixing them with a large quantity of water, and breaking them to pieces by a continued mo- tion of this fort of mill made with four vanes, or flaps of . thin wood, which was kept for fix or eight hours in a con- . tinual motion by means of a larger wheel, fuch as the lapi- daries polifh Hones with.

There is no doubt but that the inftrument, ufed by the Count, is of very great ufe, and that the refult of the opera- tion is a very valuable form of medicine ; but it is not a fait, but an extremely fine extract, containing the gummy, refinous, and faline parts of the body, and is a form capable of being reduced to powder, and eafily adminiftered, as it contains the virtues of the plant it is made from in an ex- tremely fmall compafs, and is capable of ready folution in aqueous fluids. It is certainly a form of medicine worthy to be brought into pradfice, and muft be a very proper way of adminiftring the more bulky medicines to children, and perfons of tender conftitutions.

To give a proper view of the nature of thefe preparations, and their difference from the extra£ls made in the common manner, it may be proper to enter, in fome degree, into the manner of preparing the two forms. The common ex- tracts of the (hops are made either from the juices of fuc- culent plants, as houfcleek, purflain, or the like; or from a ftrong decofiion of the other drier plants in common water, which when feparated from the coarfer parts by fub- fidence, filtration, or the like means, are evaporated over a balneum maria: to the confidence of a thick honey. There will, in procefs of time, an effential fait feparate itfelf from thefe extracts, and many plants have, in the decocti- ons, a large quantity of a fine fubftance, which will never be made to pafs the filter : and the extracts, made by this means, contain the oil, the gummy and refinous parts of the plants, and their effential falts, though this js but in a very inconflderable quantity. Thefe are the common ex- tracts of plants.

The method of making thofe extracts, called Count Laga- rais's falts, is this. They choofe a glafs veffel, capable of holding fix or feven pints, and having a wide mouth ; into this they put an ounce of bark, fena, guaiacum, or whatever other vegetable they are to make the extract of, firft re- duced to a coarfe powder. They pour on this two pints and an half of rain water, or diddled water, and then taking the veffel to the place where the mill is fixed, they raife it fo high, that the body of the mill is in the middle of the liquor; they then cover the top of the veffel with a wet bladder, that the froth may not be thrown over, and then turning the large wheel, they make the mill move round very fwiftly in~"the liquor for fix or feven hours together ; after this they let the liquor fettle for an hour or two, till only the finer parts of the body remain fufpended in it, and then pour it off into a number of flat China, or ftone ware difhes, putting only a fmall quantity into each difh, and thefe they fet in the fun, or over a balneum marise prepared on purpofe ; for fhould they attempt the evaporation in a fand-heat, the fmall quantity of extract in each difh would be burned. When the whole is evaporated to a drynefs, there remains on the whole inner furface of the difhes a thin cruft of an extract, which is to be feparated by fcraping it off with a piece of ftiff paper, and referved for ufe. This always breaks up in fmall fcales, which have a very fhining furface on that part where they adhered to the difhes, and it feems that this has given occafion to fome to believe, that they were particles of tea] fait.

There is no doubt, but this method of procuring a power- ful extract might be of great ufe, in regard to all thofe fub- ftances which water can have power to penetrate ; but it is not eafy to give credit to its being able to make the like valuable medicines from the metals, though that has been pretended. Gold and filver are pretended to be operated on in a powerful manner by it, but there feems a fallacy in this, fince even iron itfelf, which is much more penetrable by water than thofe metals, yields but little virtue to it, two ounces of the filings of this metal yielding, with the utmoff care and accuracy, only about four grains of a white earthy

SAL

matter, which is alfo much more likely to be a part of the water than of the metal.

The falts of the metals, as the Count called them, which were prepared by this means, were always fufpected to bold fome faline quality, which they owed to the menftruum, which, whatever was pretended, was not fimple water, and a ftrict examination of them always difcovered a marine fait among them. It is true indeed, that according to Lan- gelot's method of grinding, fome leaves of gold were re- duced, by the addition of a very fmall quantity of water, into a liquor, from which, on diflillation, a few red drops were feparated ; but it is to be obferved, that as Langelbt's method is the grinding the fubftance with great vehemence, and for a long time, in an iron mortar, with a pcftii of the fame metal, there is reafon to fufpecl:, that what was found to come forth in red drops was a folution of iron, not of gold, as was pretended by thofe who firft prepared them. It is not to be doubted, but the method of evaporation of Count Lagarais's medicines is of great ufe, fince no other can fo well retain the finer parts of the medicines. Mr. Geof- froy tried it on rofes, violets, and fome other flowers, and found great reafon to wifh that all the medicinal extracts could be prepared in the fame manner; but the method is impracticable, when medicines are to be prepared for gene- ral ufe ; for though the mills might be made to be mov-?d in great numbers at once, by a current of water, and fo this part of the work performed with tolerable eafe, yet the eva- porations, in fuch quantities, could by no means be made in any tolerable room, or time, and they muft be evapo- rated as foon as made, fince they very quickly turn four, and lofe all their virtues. Mem. de TAcad. Scienc, Par. 1739. See Extract, Lixivial Salts. It may appear very natural, from confider- ing the common method of making the lixivial falts, that they fhould be all of them one and the fame fubftance ; and as the greater part of them agree perfectly, not oidy in tafte, fmell, and colour, but even in their effedts, in the niceft chemical operations, in which it appears wholly the fame thing, whether one or another of them be employed ; many, even of the molt, celebrated cbemifts, have pofi- tively declared that they are all the fame, and Kunkell has pofitively afferted this on many repeated experiments, allowing them no other difference, than that fome contain more, fome lefs earth ; and this he affirms not to be owing to the different fpecies of the plant, but from certain acci- dents in the burning.

This account, however fpecious, is not true ; for though there are many of the lixivial falts procured from different plants, which, on many trials, appear alike, yet there are ibme that greatly differ from the common kinds ; as that of tamarifk, which wants the greateft of all their characters, in that it is no alkali, but a true falfalfus ; and befide this, there are probably many other as remarkable differences in others, which happen not yet to have been obferved. Mr. Bourdehn, of the Paris Academy, having obferved, that among the lixivial falts fome were greatly more, fome greatly lefs alkaline, and this laft mentioned kind not at all, determined to fcarch minutely into their differences in this refpect. In this attempt he tried the produce of a great number of different fruits and flowers of plants, many of which gave lixivial falts, confiderably different from one another; but nothing more frrengthened his opinion of the effential differences of fome of them, than the fait of guaia- cum, which proved to be little more an alkali than the fait of tamarifk, and which he is of opinion may be pre- pared in fuch a manner, as not to prove at all alkaline. Mem. de 1'Acad. Par. 1728. SecLixivious, CycL The opinion of the fixed falts, drawn by elixiviation from all plants, being the fame, having greatly prevailed, Mr. Gmelin, of the Peterfburg Academy, went through a mul- titude of experiments with the falts, made carefully from a great number of different plants, on a number of different liquors ; fome mineral acids, others folutions and impreg- nations of different fubftances ; and by thefe he found that they had very different qualities, befide their diffe ring greatly in the degree of their alkaline power, which had been look- ed upon as their effential character.

He obferves, that thefe falts are not to be obtained pure by any means, except a violent and repeated calcination ; and that this is not the method ufed with the feveral falts made for medicinal ufe, and confequently that they are all im- pure. The additional matter, which makes thcfefalts im- pure, is either an earthy, an oily, an acid, or a volatile al- kaline fubftance, according as the plant, while recent, a- bounded with one or the other of thofe principles, or as their mutual connexions with one another were more or lefs ftrong in each. As therefore the feveral fpecies of plants are well known to abound with different principles, it muft neccffarily follow that the lixivial falts, obtained from them in the common way, muft differ in their nature and proper- ties, as the acid abounds in one, the volatile alkali in an- other, and the earth or oil in a third. This difference unqueftionably owes its origin to the nature

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