acid,a.andn.|ˈæsɪd|[a.mod.Fr.acide (Cotgr.1611) orad.L. acid-usadj.of state,f.acē-re to be sour (root ac- sharp).]A.adj.1. a.Sour, tart, sharp to the taste; of the taste of vinegar.1626BaconSylva vii. §672It[sorrel]is a cold and acid herb.1676inPhil.Trans.XI. 614These crystals are pure vitriol, acid-austere.a1704LockeCond. Underst. §40The acid oil of vitriol is found to be good in such a case.1855BainSenses &Intell.ii. ii. §13. 162 (1864)The sour or acid taste is much more uniform in its nature than either the saline or the alkaline.1866J. T. Syme inTreas.ofBot.830This plant has a pleasant acid taste.b.acid drop, short for acidulated drop: a sweet made of sugar strongly flavoured with tartaric acid. Also acid tablet (formerly acidulated tablet).1836Mag.Dom.Econ.July 28Acid Drops.—Boil one pound of lump-sugar, one cupful of water, and one table spoonful of vinegar till it snaps like glass.1889Pract.Confectioner 1 May 5/1Run through the small acid-drop rollers.1902Boy's Realm 29 Nov. 388/4He should carry about him a few acid tablets, and slip one of these in his mouth when the desire for smoking is particularly strong upon him.fig.1869Porcupine 17 July 149/3Saturday Review Acid-drops may do for babes—strong men want sharper sauce.1960Times 27 Oct. 15/2Her best characters are viewed satirically..but, even so, many of her acid-drops are soft-centred.2. a.fig.1775BoswellJohnson II. 370 (1826)Beauclerk..said in his acid manner, ‘He would cut a throat to fill his pockets, if it were not for the fear of being hanged.’1826DisraeliViv. Grey vi. vi. 346A hale old woman, with rather an acid expression of countenance.1851RuskinStones Ven. I. xxiii. 264 (1874)The mere dogtooth is an acid moulding, and can only be used in certain mingling with others, to give them piquancy; never alone.b.Applied to an intense colour.1916H. G. WellsMr. Britling sees it Through i. v. 175The dark turf at the wayside..became for a moment an acid green as the glare passed.1923D. H. LawrenceBirds, Beasts & Flowers 151You acid-blue metallic bird.1959Listener 29 Jan. 209/1The acid blues and beautifully placed creamy whites are not to be met with outside Russia.3. a.Chem.Having the essential properties of an acid. See B. (Not separable in early use from 1.)a1727Newton quoted inChambers'Cycl.s.v.Acid,In decompounding sulphur we get an Acid salt.1747BerkeleySiris 124The mild native acids are observed more kindly to work upon and more thoroughly to dissolve metallic bodies than the strongest acid spirits produced by a vehement fire.1812Sir H. DavyChem.Philos.48The analysis of mineral bodies..by the application of acid and alkaline menstrua.1873WilliamsonChem.§58The solution has a slightly acid reaction to litmus-paper.b.Derived from an acid by partial exchange of the replaceable hydrogen, as acid radical, acid salt.1868J. P. CookeChem.Philos.(1870) ix. 83The metallic atoms are basic radicals, while the non-metallic atoms are acid radicals.1869[see anhydride].1869RoscoeElem.Chem.132Thus[from dibasic acids]two classes of salts are derived; the so-called acid salts, where only one atom of hydrogen has been replaced, and the neutral salts, where both atoms have been replaced by a metal. Hydrogen potassium sulphite HKSO₃ in an acid salt.1870[see anion].1873FownesChem.I. 339The acid sulphite is very soluble in water, and has an acid reaction.1947G. ThomsonAtom (ed.3) xiv. 128When the salt is formed, water is eliminated and takes with it the oxygen, from the metallic oxide, leaving the metal in combination with the residue of the acid, called the Acid Radical.c.acid dye, a dye used in an acid bath for dyeing textiles, etc.; also one used as a stain in certain kinds of microscopical and histological research. So acid colour, the dyestuff itself or the resultant colour.1888Jrnl.Soc.Dyers & Colourists IV. 107When wool is boiled in a neutral solution of these acid dyes it merely becomes tinted.1888A. SansoneDyeing vii. 140There is no end to the shades that can now be produced by means of these acid colours.1902Encycl.Brit.XXVII. 557/1Acid Colours. These dyestuffs are so called because they dye the animal fibres wool and silk in an acid bath; they do not dye cotton... The colouring matters themselves are of an acid character.1942G. BourneCytol.& CellPhysiol.i. 2Acid dyes cannot effectively be used supravitally in this way..to show pre-existing structures; but some of them can most profitably be injected into living animals, certain of whose cells will take them up in a characteristic way.d.Of, pertaining to, or resulting from an acid process of steel manufacture in which the converter or furnace is lined with acid refractory, and acid slag is used for refining. (Cf.basic a. 2 c.)1903H. H. CampbellManuf.&Prop.Iron & Steel 8The growth of the basic Bessemer practice made it necessary to have a distinguishing name for the old way, and it is therefore called the acid process.Ibid.23If acid steel does not follow exactly the same law as basic steel, then it is certain that they are not the same.1944Jrnl.Iron & SteelInst.CL. 177 P,Comparing the 18 basic steels with the 30 acid steels, there is practically no difference in the mechanical-test results.e.acid value, a measure of the free acid content of a substance.1911Jrnl.Soc.Chem.Ind.15 Apr. 409/1Acid value of oils and fats.1912ThorpeDict.Appl.Chem.(ed.2) III. 767/2The acid value indicates the number of milligrams of potassium hydroxide required to saturate the free fatty acids in one gram of an oil or fat.1931C. EllisHydrogenationOrg.Subst. lxi. 853A method of utilizing the acid values of sodium acid sulphate or bisulphate is recommended by Becquevort and Deguide.f.acid rain: rain with significantly increased acidity as a result of atmospheric pollution.1859R. A. Smith inQ.Jrnl.Chem.Soc.XI. 232The stones and bricks of buildings..crumble more readily in large towns where much coal is burnt... I was led to attribute this effect to the slow, but constant, action of the acid rain.1929Encycl.Brit.XX. 841/1Acid rain is also directly harmful to plant life, and affects adversely the soil.1972N.Y.Times 12 June 12/3Sweden has presented to the United Nations Conference on the Human Environment a ‘case study’ of the effects in Sweden of acid rains generated largely by emissions from the industrial belt stretching from the Ruhr to the British Midlands.1980FinancialRev.(Austral.) 18 Apr. 30/2Acid rain is generally caused by the release of oxides of sulphur and nitrogen into the atmosphere where they may combine with water to form sulphuric acid and nitric acid molecules which then fall to earth with rainwater.1984DailyTel.2 Jan. 8/6Acid rain is moving up the protest charts.4.Min.=acidic 2.1874LyellElem.Geol.xxviii. 497Rocks containing an excess of silica from 60 to 80 percent.are termed by many petrologists ‘acid’ rocks.B.n.1. a.Popularly, A sour substance. Chem.A substance belonging to a class of which the commonest and most typical members are sour, and have the property of neutralizing alkalis, and of changing vegetable blues to red; all of which are compounds of hydrogen with another element or elements (oxygen being generally the third element), and in the decomposition of a compound substance are relatively electro-negative, and borne to the positive pole.1696Phillips[not ined.1678],Acid in Chymistry, that sharp Salt, or that potential and dissolving Fire which is in all mix'd Bodies, and gives 'em being. Of Acids, Vitriol is the chiefest, Sea-salt next to that.1712tr.Pomet'sHist.Drugs I. 57The Edges or Points of the Acid penetrate the gustatory Nerve.a1727Newton quoted inChambers'Cycl.(1751)s.v.Acid,The particles of Acids are of a size grosser than those of water.1747BerkeleySiris 159What the chemists say, of pure acids being never found alone, might as well be said of pure fire.1791HamiltonBerthollet, Art of DyeingPref.7The improvement depends principally on the use of the acids.1814Sir H. DavyAgric.Chem.106The acids found in the Vegetable kingdom are numerous.1837WhewellHist.Induct.Sc.xiv. x,The whole fabric of chemistry rests, even at the present day, upon the opposition of acids and bases; an acid was certainly at first known by its sensible qualities, and how otherwise, even now, do we perceive its quality?1871TyndallFrag. ofSc.I. v. 161 (ed.6)Neither acids nor alkalies had the power of rapid destruction.1879McCarthyHist.Own Times I. 42Lord John Russell..was especially effective in a cold irritating sarcasm, which penetrated the weakness of an opponent's argument like some dissolving acid.b.acid test, the testing for gold by means of nitric acid; fig.a crucial test.1892G. E. GeeJeweller's Assistant 131The old-fashioned platinum alloy, in imitation of the bright gold alloys of thirty years ago, can hardly be said to have any golden tinge in its appearance. It certainly withstood the acid test very well, and this will be the only point of resemblance worthy of comparison.1912L. J. VanceDestroying Angel (1913) xi. 149Few professional beauties could have stood, as this woman did, the acid test of that mercilessly brilliant morning.1918Woodrow Wilson inTimes 9 Jan. 8/1The treatment accorded Russia by her sister nations in the months to come will be the acid test of their good will.1955Times 27 July 8/6The acid test, however, would come with the Foreign Ministers' meetings in October, when generalities had to be translated into specific agreements.c.The hallucinogenic drug LSD. slang (orig.U.S.).1966Alpert & CohenLSD (inside cover),Acid, LSD-25, lysergic acid diethylamide.1966H. S. ThompsonHell's Angels (1967) xxi. 246Contrary to all expectations, most of the Angels became oddly peaceful on acid.1967Melody Maker 2 Sept. 9People were..trying to shove STP on me, and acid.1968J. D. MacDonaldPale Grey for Guilt (1969) xii. 152‘Do you mean narcotics, girl?’ ‘That's the fuzz word. But all we had was acid and grass. Booze is a lot worse for you.’1970J. Lennon in J. WennerLennon Remembers (1971) 30,I was influenced by acid and got psychedelic, like the whole generation, but really, I like rock and roll and I express myself best in rock.1973To Our Returned Prisoners of War (Office ofU.S.Secretary of Defense) 1Acid, refers to the hallucinogenic drug, Lysergic Acid Diethylamide, (LSD).1974K. MillettFlying (1975) i. 41Stoned on pot and acid all day long, he calls it indulgence if we drink whisky.1976M. MachlinPipeline iv. 47You're stoned out of your mind again. What're you on now? Reds? C? Acid?2.to put the acid on (someone), to exert pressure on (a person) for a loan, a favour, etc. Also to ply, try, the acid. Austral.slang.1906Bulletin (Sydney) 15 Mar.,Note ‘to put the gas on’—a variant of ‘to put the acid on’,—the latter familiar slang from the mine-assayer's lexicon.1935Ibid.3 Apr. 20/1He was evidently applying the acid to ascertain if my tombstone was as good as ordered.1938J. MosesNine Miles from Gundigai 10The barber's shop's a witness-box (They ply the acid there).1945BakerAustral.Lang.vi. 124To put the hard word (or acid) on a girl, to make a request to her for favours.1947J. Morrison inCoast to Coast 1946 158They want to shift the ship at seven. That puts the acid on us.3.to come the acid (cf.A. adj.2): to behave in an ‘acid’ manner, to be unpleasant or offensive, to speak in a caustic or sarcastic manner. slang.1925Fraser & GibbonsSoldier & Sailor Words 3Coming the acid, stretching the truth; making oneself unpleasant; trying to pass on a duty; exaggerating one's authority.1936J. CurtisGilt Kid vi. 61If the queer fellow tried to come any acid he would get hit right on the razzo.1939H. HodgeCab, Sir? xviii. 259Any attempt to ‘come the acid’, so far from frightening the cabman, will probably result in the cabman's giving him a little fatherly advice.1953‘H. Cecil’Nat.Causes vii. 95Why come the old acid? Not even a ‘sit down, old man—’.4.In numerous combs. in Chem.(seealso A. 3), as acid-base; acid-embossing, embossing (of glass) by treatment with acid; acid-fast[Fast a. 1 h]a., resistant to decolorization by an acid when stained: saidesp.of bacteria (hence acid-fastness); acid-forming a., producing or yielding an acid; acid-free a., not containing an acid; acid-proof[proof a. 1 b], a., (a) impervious to acid; capable of resisting the deleterious action of acid, (b)=acid-fast.1917Chem.Abstr.3050 (caption)Observations on acid-base equilibrium in the body.1925W. MorseAppl.Biochem.575Modern biochemistry considers the mineral substances of the food..as participating in the acid-base metabolism of the body.1937McGrath & FrostGlass inArch.& Decoration 405The French artist-technicians, Paule and Max Ingrand, have demonstrated more delightfully than anybody else the possibilities of acid-embossing and sand-blasting.1904Med.Ann.578With regard to examination of sputum, it must be remembered that several observers have reported ‘acid-fast’ bacilli which were apparently non-tubercular.1909Cent.Dict.Suppl.,Acid-fastness.1925C. H. BrowningBacteriol.viii. 175Ehrlich showed, however, that tubercle bacilli possessed the remarkable property of acid-fastness, that is to say they withstood the decolorising action of strong acids..when once they had been stained.1869H. E. RoscoeElem.Chem.xvii. 175Oxides may be divided into (1) Basic oxides; (2) Peroxides; (3) Acid-forming oxides.1914Lancet 28 Mar. 908/1The air of New York schools was examined for the acid-forming streptococci.1930PaperTerminol.(Spalding & Hodge) 1Acid free, paper free from any acid or other material likely to have deleterious effects.1934R. F. InnesCauses & Prevention Decay in Leather 1/2Modern knowledge demands that leather should not only be ‘Acid free’ but ‘Protected’ as well.1868G. A. SalaNotes &Sk.ParisExhib.xxvii. 387They[sc. safes]are also stated to be acid proof.1909Installation News iii. 271[Conduit]protected by an even and not too thick coating of acid proof, moisture resisting, flexible enamel.1913DorlandMed.Dict.(ed.7) 32/2Acid-proof, same as acid-fast.1937E. J. LabarreDict.Paper 95/2Acid proof paper is generally wood Manilla, Kraft or Rope Wrapping which has been treated to resist acids or acid fumes.5.(In sense 1 c above).a.SpecialCombs.acid freak,[freakn.¹ 4 c], head[headn.7 e], one who habitually takes the drug LSD; acid rock,(seequots.1971); acid trip, a hallucinatory experience induced by taking the drug LSD.1969*Acid freak[see freakn.¹ 4 c].1966*Acidhead[see psychedelic a. 1 b].1968A. DimentBang Bang Birds viii. 142Acid heads are such nice people they want to be friends with the whole world.1974M. C. GeraldPharmacol.i. 13With the realization that the..‘acid head’, and ‘dope addict’ also reside in ‘good, middle-class homes’, the public..has become increasingly concerned.1966*Acid rock[see psychedelicallyadv.].1971E. E. LandyUndergroundDict.22Acid rock, psychedelic music...It emphasizes electronic sounds; has a very prominent beat, repeated sounds.Ibid.,Acid rock is considered to be the musical equivalent of an LSD-induced state.1977Zigzag Aug. 24/2The highlight was the closing ‘Rock And Roll is Dead (And We Don't Care)’, a guaranteed showstopper intro'd by Tommy's entirely vicious parody of an acid-rock axe hero.1967*Acid trip[see freaky a. 2].1974K. MillettFlying (1975) iii. 356Today a day so beyond possibility that I am flowing through it like a fairy tale. Or an acid trip.1982T. GunnOccasions of Poetry ii. 182The acid trip is unstructured, it opens you up to countless possibilities.b.Simpleattrib.andComb.uses.1966Life 25 Mar. 30c/1A bad trip—a sudden vision of horror or death which often grips LSD users when they take it without proper mental preparation—overtakes a teen-age girl at an ‘acid party’ near Hollywood's Sunset Strip.1966H. S. ThompsonHell's Angels (1967) xxi. 246My own acid-eating experience is limited in terms of total consumption, but widely varied as to company and circumstances.1969Listener 24 Apr. 578/2For these ‘acid drop-outs’ the frontier between reality and fantasy is blurred.1970A. TofflerFuture Shock xiii. 260Blending the blue jeans of the beats with the beads and bangles of the acid crowd, the hippies became the newest..subcult.1976Time Out 2 Apr. 51/5Genuine acid-punk rockers.1977Rolling Stone 30 June 124/1If they ever do play either the dark side or light side of the moon, rest assured they will bedeck those static craters with helium-filled pigs and acid-hued light shows.Add:[B.][1.]d.ellipt.for *Acid Housen.1. Freq. attrib.1988Smash Hits 19 Oct. 9/2They dress up in silly clothes..and trot off to nightclubs and sort of wave their arms in the air and..jump about shouting ‘accceeeiiiiiiiid’ all the time to ‘Acid’ music (which is like House music except it's entirely tune-free).1989Melody Maker 14 Oct. 48/1In the aftermath of the first waves of Acid and Balaeric[sic], clubbers have been offered, in no chronological order, dance music under the names of freestyle, raggamuffin and swingbeat.1991Face Feb. 79/1The early acid/Balearic scene was an amiable mixture of gay and straight, and stories of Millwall fans stroking each others tattoos in bouts of Ecstasy-inspired affection became part of club lore.Add:[A.][3.][c indigo][f.][/c] Similarly acid air, acid precipitation.1955Tellus VII. 253/2The principal features of the chart of Fig. I are: (a) the region of acid precipitation along the west coast.1974Water ResourcesRes.X. 1134/2Evidently, acid precipitation was occurring in the Northeast as early as 1952.1982Washington Post 3 Aug. a10/2The suspected culprit is ‘acid air’, made up of sulfuric acid and related pollutants.1991N.Y.Times 18 Feb. 4/3The striking figure ofSt.Mark..its marble nose has been stunted by acid air and water potent enough to destroy parts of the figure's fingers and of the Bible in its hand.[B.][1.][b.]spec.in Comm.(further example); hence acid test ratio, a liquidity ratio usedesp.in estimating the ability of an enterprise to meet its current obligations,usu.calculated as the ratio of liquid assets to current liabilities.1928Wall & DoningRatioAnal.Financial Statements v. 90A great many analysts have supplemented their measure of the total current assets against the total current liabilities by a comparison in which the inventory does not play a part. This has been called the ‘acid test’.1936MacFarland & AyarsAccounting Fundamentals xxx. 477The acid test ratio is the expression of the relationship of cash, receivables, and marketable securities.., to the current liabilities.1978Business Week 11 Dec. 112The acid-test ratio—cash, cash equivalents, and receivables divided by current liabilities—declined to .94 from 1.3 the year before.[4.]acid-loving Biol., thriving in acid conditions.1910Jrnl.Med.Res.XXII. 155Moro believed that it was in reality an ‘*acid-loving’ organism.1985A. TylerAccidental Tourist xix. 307For azaleas and what else do you have, andromeda, acid-loving plants.1994DailyTel.11 Oct. 4/6The bog..is home to the sundew, a rare acid-loving carnivorous plant, cotton grass, bog rosemary and rare mosses.▸ colloq.(orig.U.S.). on acid: (a) (of a person) under the influence of LSD; (b) fig.in —— on acid:—— as it might be if perceived while under the influence of LSD; a bizarre or fantastic version of——.Cf.onprep.12f.1967H. S. ThompsonHell's Angels xxi. 238Contrary to all expectations, most of the Angels became oddly peaceful on acid.1968N.Y.Times 6 Oct. d32/2Strains of Gershwin and Bernstein flash through Laura's songs... But it is Bernstein without Bernstein's sentimentality, and Gershwin perhaps on acid.1977N.Y.Times 10 Aug. 59/1The film, a kind of ‘Father Knows Best’ on acid, showcases most of the director's worst qualities.1989C. S. MurrayCrosstown Traffic ii. 48Wired on acid..Hendrix..threw in every scene-stealing stage trick he'd ever learned.1992Face Apr. 73The Caribbean restaurant..is a primary-coloured mish-mash of painted wood: a Bacardi advert on acid.2000N.Y.Mag.7 Aug. 72/2To me, this religio-erotic love bath just sounds embarrassingly awful, rather like Rachmaninoff on acid.