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In like manner pure fpirit of nitre faturated with the alkaline fpirit of fal armoniac, makes a kind of volatile nitre, and thus affords an opportunity of examining, by experiments, whether the great things expefled from a volatile nitre by the chemifts, will be performed by it or not. Experiments of this kind are extremely worth profecuting. It is not cer- tain whether any Menjiruum will diffolve any fubftance with- out the affiftance of fire, as no experiment could ever be made in any place deftitute of all fire ; there being evidently fire in our utmoft known degree of cold ; and we all know that Menjlruunu, of whatever kind, act greatly the better for being aflifted by heat.
Menflruumt can fcarce act as fuch, unlefs reduced to a fluid form, or at leaft approaching thereto ; this is chiefly given them by means of fire, air, water, and triture : Thefe are the four caufes which ufually excite the latent powers of Men- Jlruums. Certain Menflruums contain a caufe within them- felves apparently capable of exciting motion, though in reality it depends upon the near approach of fome other body. Thus if a good loadftone be fufpended by a thread, and hang . at reft in a great degree of cold, it will feem to have no active .virtue ; but if iron come near it, a motion is produced in both thefe bodies, till they come together, and remain in con- tact ; and this kind of power generates motion fpontaneoufly, without the afliftance of any fire fenfiblc to us, and is not ex- cited by motion. So likewife ftrong fpirit of nitre confined in a clofe veflel, yields an acid fume conftantly playing about the furface of the liquor, and Miiing out whenever the veffel is unftopped. So alfo the alkaline fpirit of fal armoniac yields ■a fume never obferved to be at reft ; and the fpirit of this fait, made with lime, yields a fume much more volatile and move- able : All the bodies of this kind therefore ftrangely retain, and ftrangely excite motion. We are always to remember alfo that air, even in the coldeft places, has always a ftrong vibratory motion, and therefore may often excite thefe mo- tions in thefe bodies ; as on the other hand folutions are often immediately performed by means of the motion peculiar to the Menjiruum arifing from it j while another motion of a different kind, and proceeding from a different caufe, would not produce the effect. Thus, for inftance, if a fine piece of Englifli chalk be calcined in a ftrong fire, or even in the .focus of a burning-glafs, it will fcarce alter its nature by this violent motion, nor again by being expofed to a hot or cold air, either at reft, or agitated by winds ; and though if long boiled in water, or a brine of fait of tartar, it will notdiffolvej yet it immediately melts and difappears when put into cold vinegar. Whence we fee there is a very great difference be- tween the motion excited by the reciprocal force of the folvent and folvend, and the motion excited by fire, air, water, and impulfe. The acrimony of a Menjiruum, with refpect to a human body, fo as to excite pain, corrode or confume the parts thereof, is no fign that fuch a Menjiruum is fuited to diffolve other bodies, as appears from oil of vitriol, fpirit of nitre, fpirit of fait, and aqua regia, which though they rea- dily confume flefh, yet do not confume or diffolve wax and fulphur, though thefe two may be eaflly diffolved in the body. Many bodies incapable of folution in certain Menflruums, may be fuited for diffolving therein, by being previoufly dif- folved in other Menflruums. Thus if common fulphur be boiled ever fo long in alcohol, it diffolves no more than a ftone in water ; but if the fulphur be firft melted with fait of tartar into a dufky mafs, the alcohol will then diffolve it ; fo alfo powdered antimony remains untouched after boiling in alcohol ; but if firft boiled to a dry mafs in an alkaline lixi- vium, this mafs prefently yields a golden tincture to alcohol. Some chemifts have conceived fo highly of this regular and fucceffive application 'of different Menflruums, particularly Mr. Boyle and Mr. Hombcrg, that they fay even metals may by this means be refolved into their component running mer-' cury and fixing fulphur. Thus they affert, that if filver be firft diitolved in fpirit of nitre, and then long digefted with pure fixed alkali, and afterwards feveral times fublimed with fal armoniac, it will at length, by means of thefe refufcitating falts, afford a true running mercury ; in which operation the acids procure an entrance for the alkalis into the fubftance of the metal, as the fixed alkalis procure admiffion to the volatile ones, which elfe could not enter. Boerhaave waves difputing upon the point, whether the metals can be thus refolved into their run- ning mercuries, and only affirms, that after many trials, he was never able to effefl it. Barb. Chem. part i. p. 562. feq.
It is an error to think a Menjiruum cannot be too ftrong. Oil of vitriol diluted with feveral times its weight of water, dif- folves iron beft. So aqua fortis diluted works beft in lead. And Mr. Boyle makes the like obfervation as to the folution of filvet. Works Abr. vol. 1. p. iSc. Animal Menstruum. There are of the animal Menflruum! very many both of the natural and artificial kind ; the natural are Blood, ferum, gall, urine, faliva, rennet, whey, butter- milk, tic. moil of which, being properly employed, will ei- ther produce or difcharge colours, and might be made fer- viceable in the painting and dying trades. Thus recent urine difcharges the common ink out of linnen, &c. Blood affords, by proper management, the noble Pruffian blue ; and gall is
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a natural yellows well deferving to be treated in the manner 01 blood in that preparation. Of the artificial kind are the (pint of urine produced by chemiftry, which ferves to produce- alter and deftroy a vaft number of colours. The liquors di- ltilled from recent, or fermented whey, buttermilk, £sV might be alfo found of great value ; and varioufly compound- ing thefe feveral animal fubftances, even by random trials, or chance experiments, new difcoveries in colours might be made ; though much more, probably, by a right reafonin^ and analogy. As for inftance, the common bones burnt to" a blacknefs, being found to afford the bone black, the expe- riment was eafily transferred to ivory, and fo the ivory black was difcovered : And fo of the reft. »om's LeBures. p. 18? Menstruum Peracutum. Mr. Boyle gives the name of Men- jiruum peracutum to a Menjiruum made by pouring on the re&fiedoil of butter of antimony as muchltrong fpirit of ni- tre as would ferve to precipitate out of it all the bezoarticum minerale; and then with a fmart fire diftilling off the liquor which would come over, and cohobating it upon the antimo- nial powder. Works Abr. vol. 1. p. 260, 377. He put fome highly refined gold into a large proportion of this Menjiruum peracutum, where it diffolved (lowly and quietly ; and he found at the bottom of the glafs a confiderable quan- tity of a white powder, which the Menjiruum would not touch, and which was alfo indiffoluble in aqua re»ia. The folution of gold being abftrafled, and the gold agam reduced into a body, yielded, upon a fecond folution, more of the white powder. This powder he melted down into a metal, anfwermg m colour, malleability, folubility in aqua fortis. and in bitternefs to the tafte of that folution, to filver. Hence he infers, that notwithftanding the fuppofed unchangeablenefs of gold, this experiment fhews it to be really changeable into filver, or at leaft into a new kind of metal very different from gold. And he therefore concludes, that there is no impofli- bihty in the nature of the thing, that one metal fiiould be tranfmuted into another. Ibid. p. 260 — 262. By diffolving gold in this Menjiruum peracutum, Mr. Bovld alfo tells us, he made the gold rife in the retort, in the top and neck of which it was found in the form of yellow and reddifh fublimate. Works abr. vol. r. p. 263, 377. We do not find that Mr. Boyle gave the name of Menjiruum peracutum to the Menflruum he extraded from bread, as it is faid he did, in the Cyclopa:dia, under the head Men- struum. See Boyle's Works Abr. vol. 1. p. 34, 49. MENTHA, Mint, the name of a well known genus of plants the characters of which are thefe: The flower confifts of one leaf, and is of the labiated kind ; the upper lip is arched, and the lower is divided into three fegments ; and the whole' is fo difpofed, that at firft fight the flower appears a four-leav'd one, or at leaft one regularly divided into four fegments. The piftil arifes from the cup, and is fixed in the manner of a nail into the hinder part of the flower, and furrounded with four embryos which afterwards become fo many feeds, and are contained in the cup of the flower. The fpecies of Mint, enumerated by Mr. Touraefort are thefe : 1. The common round-Ieav'd wild Mint. 2. The purple-flower'd round-leav'd wild Mint. 3. The verticil- lated garden Mint, with the fmell of bafil. 4. The common curled-leav'd verticillated Mint. 5. The round-leav'd fpiked curled Mint. 6. The beautiful Danifll or German curled Mint. 7. The round-leav'd fpiked wild Mint. 8. The great roundifli-leav'd marfh or Water Mint. 9. The great round-leav'd Marfh Mint, with variegated leaves. 10. The hairy verticillate field Mint. 1 1. The rounder-leav'd verticil- late field Mint, with an aromatic fmell. 12 The fpiked Mint, with variegated leaves. 13. The narrow-leav'd fpiked Mint. 14. The fmooth narrow-leav'd wild Mint with rugged leaves, and a ftrong fcent. 15. The long blackifh-leav'd lefs hairy wild Mint. 16. The common thick fpiked pepper Mint. 17. The long-Ieav'd horfe Mint. 18. The longer-leav'd water Mint. ig. The water Mint', commonly called Pennyroyal. 20. The common white- flowered Pennyroyal. 21. The water Mint, called by many authors male Pennyroyal. 22 The fmalleft woolly water Mint. 23. The favory-leav'd water Mint. Tourn. Inft. p. 189. See the article Mint. MENYANTHES, Buckbean, in botany, the name of a fenus of plants, the characters of which are thefe : The flowercon- fifts of one leaf, is funnel-fliap'd, and divided into feveral fegments at the edges. From the cup there arifes a piftil, which is fixed in the manner of a nail to the hinder part of the flower, and afterwards becomes a fruit or fhelly cafe ufually of an oblong figure, bivalve, and full of frnall round- ifli feeds.
The fpecies of this plant, enumerated by Mr. Tournefort are thefe : I. The broad-leav'd trifoliate marfh Menyanthes called by many writers, Trifolium palujlre, and by us, Mar/ti Trefoil, or Buckbean. 2. The narrow-leav'd trifoliate marfh Menyanthes. And 3. The American white-flower'd Meny- anthes, with leaves like thofe of the water lilly. Tourn. Inft, p. 117.
The characters of Menyanthes, according to Linnseus, are thefe : The cup is a perianthium confuting of one leaf, di- vided into five fegments at the end, and is placed erect, and
remains
