Page:Cyclopaedia, Chambers - Volume 1.djvu/67

 A C I

( « )

A C I

The German Difpenfatories abound with medicated Vine- gars, chiefly aim'd againft peftilential Difeafes : but they are •not ufed among us.— The College retains Come of 'em, as the jcetum theriacale Norimbergenfe, but it is never prefcrib'd. ACHAT, in our "Liw-Ffeticb, fignifies a ContraS, or Bargain.

Purveyors were by Aft of Parliament 3 S Ed. III. ordain- ed to be thenceforth called Achators. See Purveyors.

ACHE, or Ach, a painful Ailment in any part of the Bo- dy. See Pain, and Disease.

Aches are either Scorbutica, Rheumatick, owing to vio- lent Strains, or the like.

Head-hcu. See HEAB-yftZ;, and Cefhalalgy ACHERNER, or Acn miner, in Aftronomy, a Conflel- lation of the firfl Magnitude in the Sign 'Pifces — Its Longi- tude, Latitude, gfc. See under the Article Pisces.

ACHILLES, a Name which the Schools give to the principal Argument allcdg'd by each Soft of Philcfophers in their behalf. See Sect. _

In this Ssnfe, we fay, this is his Achilles ; that is, his Mailer-Proof : Alluding to the Strength and Importance of Achilles among the Greeks. Item's. Argument againft Motion, is peculiarly term d an

Achilles. That Philolbpher made a Comparifon between

the Swiftnefs of Achilles, and the Slowncfs of a Tortoife ; whence he argu'd, that a flow Moveable that precedes a fwift one by ever fo fmall Dittance, will never be outrun by it. See Motion.

The antient Botanifls gave the Name Achillea, to feveral Plants • one of which is faid to be the fame with our Mil- lefolium ; and took its Name from Achilles; who, having been the Difciple of Chiron, firft brought it into ufe for the Cure of Wounds and Ulcers.

'the Tendon of Achilles, Corda Acbillis, is a large Ten- don, form'd by the Union of the Tendons of the four Mufcles of the Foot, called Extenfires. See Tendon, and Foot.

It is fo called, becaufe the fatal Wound whereby Achilles is faid to have been flain, was given there.

ACHILLE1S, or Achilleid, a celebrated Poem of Sta- tins, wherein he propofed to deliver the whole Life and Ac- tions of that Hero. See Poem.

It only takes in his Infancy, the Poet being prevented from proceeding, by Death.

The Achilleid is of the Heroic or Epic Kind ; but ex- tremely faulty in the Plan, or Fable. See Fable, &c.

'Tis a Point controverted among the Criticks, whether the whole Life of a Hero, e.g. of Achilles, be a proper fub- jea Matter of an Epic Poem. See Eric, and Heroic.

ACHOR, Achores, in Medicine, the third Species or Degree of a tinea, or Scald Head. See Tinea.

Achores are a fort of Spreading Ulcers, which break the Skin into a Number of little Holes, out of which oozes a vifcid Humour. — Achores only differ from Favi in this, that their Holes are fmaller.

ACHRONICAL, in Aflronomy, is applied to'theRifing of a Star when the Sun fets ; or the Setting of a Star when the Sun rifes. See Rising, and Setting.

The Achronical Rifing of Mars, who is then found to be nearer the Earth than the Sun, has been one great Occafion of exploding the antient 'Ptolemaic Syftcm, which places the Sun in the Centre of the World, and Mars beyond the Sun. See Earth, Mars, igc.

The Achronical is one of the three Poetical Rifings and Settings of the Stars. See Poetical. The Word comes from the Greek a, and %e?V©-, Time. ACID, Acidum, any thing which affects the Tongue with a Senfe of Sharpnefs, and Seurnefs. See Taste. Acids are ufually divided into manifeft and dubious. The Manifeji Acids, are thofe above defined, which im- prel-s the Idea fenfibly. — Such are Vinegar, and its Spirit 5 the Juices of Citrons, Oranges ; Spirit of Nitre, Spirit of Alumn, Spirit of Vitriol, Spirit of Sulphur for Campanam, Spirit of Sea Salt, &c. See Vinegar, Nitre, Vitriol, Alumn, Sulphur, &c.

'Dubious Acids, arc thofe which do not retain enough of tit&Acid Nature to give fenfiblc Marks thereof on theTafte, but agree with the Manifeji Acids in fome other Properties, faificient to refer 'em to the fame Clafs. — Hence it appears that there are fome Characters of Acidity more general than that of the fharp Tafle ; tho 'tis that Tafle is chiefly regard- ed in the Denomination.

The great and general Criterion, then, of Acids, is, that they make a violent Effervefcence, when mix'd with ano- ther fort of Bodies, called Alkalies. See Effervescence.

y/et is not this Property alone univerfally to be depended on. to determine a Body an Acid, without the joint Consi- deration of the Tafte, and the Changes of Colour produ- cible in other Bodies thereby. — To distinguish dubious Acids from Alcalies, mix 'em with a blue Tincture of Vio- lets : If they turn it red, they are of the Acid Tribe ; if green, Alkaline. See Alkaly.

Acids are all of the Tribe of Salts ; and compofe a parti- cular Species thereof, called Acid Salts. See Salt.

Add, that the Acid Salts are all found to be volatile ; by which they are diflinguifh'd from the red, which are either fix'd, or at leafl have a urinous, inff ead of an acid Tailc, See Volatile, Fix'd,. and Urinous.

Some late Chymical rhiiofophers have even made it very probable, that 'tis the Acid is the faline Part or Principle in all Salts. — They consider it as a fubtile, penetrating Sub- ftance, diffufed thro' the feveral Parts of the Globe ; which, according to the differenr Matters it happens to be united withal, produces different Kinds of Bodies : If it meets a foffil Oil, it converts it into Sulphur ; if it be received into the Lapis Calcariits, it coagulates with it, and becomes Alumn ; with Iron it grows into green Vitriol ; with Cop- per, into blue Vitriol, &c.

Of this Sentiment is Sir I. Ne'Xton. — ' In decompounding ' Sulphur, fays that Author, we get an Acid Salt, of the ' fame Nature with Oil of Sulphur per Campanam ; which ( fame Acid abounding in the Bowels of the Earth, unites ' fometimes with Earth, and thus makes Alumn 5 fometimes ' with Earth and Metal, and makes Vitriol 5 and fometimes ' with Earth and Bitumen, and thus compounds Sulphur.' Opticks.

In effe&, all our native Salts, tho without any Mixture from Art, are yet found to be real Mixtures ; and their Com- pofition and Decomposition iseafily made. — * Asmanyasthey ' are, they may be all reduced, according to M. Homlerg, ' to three Kinds, to. Salt-petre, Sea-Salt, and Vitriol 5 ' each whereof has its feveral Species. Of the Combina- 1 tion of thefe with different oily Matters, are all the other £ Salts produced. By the Analyfcs we have made of 'em, c they all appear to be compofed of an aqueous, an ear- c thy, a fulphurous, and an acid Part ; but the Acid we ' hold the pure Salt : This makes our Chymical Principle ' Salt, the common Balis of all Salts ; and which, antece- ' dent to its Determination to any particular Species, appears c to be one Similar, uniform Matter, tho never found alone, t but always accompany'd with fome fulphureous Mixture or 1 other ; which determines it to fome one of the three forts ' of Foffil Salts abovemention'd.' Mem. de VAcad. R. del Sciences. An. 1708. See Principle.

The Acid, accompany'd with its determining Sulphur, ne- ver becomes fenfible to us, except when lodg'd cither natu- rally in fome earthy Matter, or artificially in an aqueous one. — In the firfl Cafe, it appears under the Form of a cry- ftalliz'd Salt 5 as Salt-petre, Sea Salt, g?c. In the fecond, it appears in form of an Acid Spirit ; which, according to the Determination of the Sulphur accompanying it, is either Spirit of Nitre, or Spirit of Salt, or Spirit of Vitriol.

What is here fpoke of the three fimple foffil Salts, may be equally applied to all the compound Salts of Vegetables and Animals, with this difference, that the latter have al- ways a larger Proportion of the earthy Matter than the fim- ple ones, when in form of a concrete Salt 5 and a larger Proportion of the aqueous Matter, when in form of an acid Spirit. — And hence we account for two important Phenome- na ; i°, That the acid Spirirs of Animal and Foffil Salts, are always weaker, and lefs penetrating, as well as lighter in Weighr, than thofe of the Foffil Salts : 2, That after a vehement Diflillation, they leave a larger quantity of ear- thy Matter behind them than the Foffil do.

The Salt naturally contain'd in Plants, may be confider'd as a Mixture of Earth, Oil, a little Water, and an acid Salt : This laft Ingredient being feparated from the Plant with a vehement Fire, fhoots into a new Salt, which fome- times retains an acid Tafle, as in the Tartar of Wine ; fometimes it affumes a Swectnefs, as in Sugar j fometimes is bitter, as in Quinquina ; and fometimes almoA infipid, as in Sage. This, M. Homberg calls the effential Salt of the Plant 5 which, by a gentle Diflillation, refolves into an infi- pid Water, an acid Liquor, and a ruddy fetid one 5 con- taining part of the acid Salt, and part of the fetid Oil of the Plant : of the Combination of which, is compofed a particular Kind of fetid Salt, fmelling like Urine, called the Volatile Salt or Volarile AJcaly Salr of the Plant : And the Caput Mortuum remaining, being redue'd into Afhes, is feparated by Lixiviation into one Part of fix'd Alcaly Salt, and another of infipid Alcaline Earth. — Add, that the ef- fential Salt always diffolves entirely in Water, even the ear- thy Part join'd with it. But if the fame Salt have been robb'd, by means of Fire, of a great part of its Acid; the ear- thy Part will not wholly diffolve, but a Sediment of infipid Eatth, indiffoluble in Water, will be found at bottom ; to which, if an acid Spirit be added, it then becomes entirely diffoluble in Water : Whence it may be fairly concluded, that the other Part of the Afhes, before diffolved in tho Water, and which after Evaporation appears in form of a fix'd lixivial Salt, was only diffolved by Virtue of the Acid it contain'd ; or as having retain'd enough of the Acid to ef- fect a Diffolution.

Again, when the Earth of the Plant, fatiated with its Acid, becomes a cryftalliz'd Salt ; no more of the fame Acid can be iniroduc'd into it : whereas the lixivious Salt drawn

irom