| 释义 |
potash, n.|ˈpɒtæʃ|
[Early mod.E. pot-ashes pl., app. ad. Du. pot-asschen (1599 Kilian, ‘quod in ollis{ddd}asseruentur, ne liquescentes effluant’), mod.Du. potasch; so Ger. pottasche, Swed. pottaska, Da. potaske; also F. potasse (1577 pottas, at Liège, Godef.), It., Pg., mod.L. potassa, Sp. potasa.]
The sense-history of potash and its derivatives is involved in the advance of chemical knowledge. The earliest term was pot ashes or pot-ashes = Du. pot-asschen, applied to the crude products. The essential substance of these, when purified from extraneous matters, was spoken of in the singular as pot-ash or potash. In 1756 this was proved by Dr. Joseph Black of Edinburgh to be a compound substance, a carbonate, the removal from which of the carbonic acid left a ‘caustic alkali’ or ‘lye’ (really the hydroxide, or caustic potash, KHO), which chemists thereafter generally considered to be the true potash (in Fr. potasse). In 1807 this, in its turn, was shown by Sir H. Davy to be not a simple substance, but to contain a new metal, of which he believed it to be the oxide. To the metal (K) he gave the name potassium, to the oxide (on the analogy of magnesium and magnesia, sodium and soda, etc.) that of potassa. Next year, Dakeel gave reasons for believing that the latter contained also water, and it was subsequently shown to be the hydroxide or hydrate (KHO), the simple oxide being the anhydrous form (K2O). The salts of potassium, in accordance with the chemical theory of the time, were viewed as compounds of the oxide, and variously named carbonate of potassa, of potass, of potash (= potassium carbonate, K2CO3), chlorate of potassa, potass, or potash (= potassium chlorate, KClO3), etc. Commercially ‘potash’ is still often applied to the carbonate; by chemists usually to the hydroxide or hydrate, caustic potash, KHO, but sometimes to the anhydrous oxide, K2O, and in names of compounds it is still often used instead of ‘potassium’, as chlorate of potash = potassium or potassic chlorate.
1. An alkaline substance obtained originally by lixiviating or leaching the ashes of terrestrial vegetables and evaporating the solution in large iron pans or pots (whence the name). Chemically, this is a crude form of potassium carbonate (more or less mixed with sulphate, chloride, and empyreumatic substances), but was long thought to be (when freed from impurities) a simple substance.
(α) orig. plural, pot ashes, pot-ashes: now applied to the crude substance.
When purified by calcination and re-crystallization, known as pearl ashes or pearl-ash.
1648Hexham Dutch Dict., Pot-asschen, Pot-ashes. 1657Knaresb. Wills (Surtees) II. 223, 50 lbs. of pott ashes. 1669Boyle Contn. New Exp. i. (1682) 37 A liquor made of the salt of Pot-ashes suffered to run in a sellar per deliquium. 1712tr. Pomet's Hist. Drugs I. 101 We sell at Paris four Sorts of Pot-Ashes. 1714Mandeville Fab. Bees (1733) I. 413 Another set of [sailors] are freezing in the north to fetch potashes from Russia. 1813Sir H. Davy Agric. Chem. (1814) 112 Herbs, in general, furnish four or five times, and shrubs two or three times, as much pot ashes as trees. 1885W. Dittmar in Encycl. Brit. XIX. 588 This calcination used to be effected in iron pots, whence, the name ‘potashes’ was given to the product; at present it is generally conducted in reverberatory furnaces on soles of cast iron.
(β) singular, pot-ash, potash: applied esp. to the purified carbonate, as a substance.
1751J. Hill Mat. Med. 801 Potash, in general, is an impure fixed alkaline Salt, made by burning from Vegetables. We have several Kinds of it in Use. 1807T. Thomson Chem. (ed. 3) II. 22 In 1756, Dr. Black proved..that the potash which the world had considered as a simple substance, was really a compound, consisting of potash and carbonic acid; that lime deprived it of this acid; and that it became more active by becoming more simple. 1811A. T. Thomson Lond. Disp. (1818) 320 Impure Potash. Impure Sub-Carbonate of Potash. Potashes. Pearl-ashes... This substance consists chiefly of subcarbonate of potash, mixed with some other salts. It is known in commerce by the name of potash; and is brought to us principally from the Baltic and America. 1861E. A. Beaufort Egypt. Sepulchres I. xv. 337 The ‘hashish el kali’..covered the ground: this is the plant from the ashes of which they make potash for soap.
†b. Used also to include the impure carbonate of soda, barilla. Obs.
1823J. Badcock Dom. Amusem. 150 Your potash should be of that kind termed barilla.
2. Chem. The hydroxide or hydrate of potassium, KHO; a hard white brittle substance, soluble in water and deliquescent in air, having powerful caustic and alkaline properties; caustic potash.
1800tr. Lagrange's Chem. I. 171 Potash is a body, which has not hitherto been decomposed; it is of a white colour, and exceedingly caustic... This substance is prepared by burning vegetables, which all contain a greater or less quantity of potash; as we shall explain under the head Carbonate of Potash. 1846G. E. Day tr. Simon's Anim. Chem. II. 128 If..caustic potash be added to the mass, a considerable quantity of ammonia is given off... When the acid is accurately neutralized with potash, it forms an easily-soluble salt. 1866Watts Dict. Chem. IV. 692 Potash..applied sometimes to the hydrate, sometimes to the anhydrous oxide of potassium, occasionally also to the crude carbonate; it is best however to restrict it to the hydrate, either in the solid state or in aqueous solution. 1869Roscoe Elem. Chem. (1871) 198 Thrown into water, one atom of potassium displaces one of hydrogen from the water, forming potassium hydroxide, or potash. 1874Garrod & Baxter Mat. Med. (1880) 125 Caustic potash is usually moulded for medical purposes into small sticks about the size of a pencil, which should be white, but are often greenish, bluish, or reddish-brown from impurities.
b. Now sometimes applied by chemists to the anhydride or monoxide, K2O, = potassa; in non-chemical works vaguely to any compound of potassium.
1843J. A. Smith Product. Farming (ed. 2) 101 The property on which this depends is, that clay invariably contains potash and soda. 1846J. Baxter Libr. Pract. Agric. (ed. 4) I. 29 Potash..is an element in most plants. 1858Thudichum Urine 195 There is only a very small quantity of potash present in the urine. 1866[see 2].
c. In names of compounds = potassa, and now in chemical use mostly superseded by potassium.
carbonate of potash = potassium carbonate; † muriate of potash, obs. name of potassium chloride; † oxygenated muriate of potash = potassium chlorate; sulphate of potash = potassium sulphate.
1791Hamilton Berthollet's Dyeing I. i. i. i. 26 Acidulous tartrite of pot-ash. 1799Med. Jrnl. I. 103 Remarks on the effects of the nitrous acid, the oxygenated muriate of pot⁓ash, &c. 1800tr. Lagrange's Chem. I. 195 Sulphate of soda may be decomposed by charcoal, phosphorus, &c. in the same manner as sulphate of potash. 1843J. A. Smith Product. Farming (ed. 2) 149 Silica enters the plant chiefly in the form of silicate of potash or soda. 1876J. S. Bristowe The. & Pract. Med. (1878) 864 The carbonate, acetate, and citrate of potash are probably the best for the purpose.
3. Short for potash-water: see 4.
1876Besant & Rice Gold. Butterfly xxxviii, They drank a whole potash-and-brandy each. 1895Cornh. Mag. Oct. 396 A stiff tumbler of whisky and potash.
4. attrib. and Comb., as potash-lye, potash muck, potash salt, potash soap; potash alum: see alum n. 2; potash-felspar = orthoclase; potash-granite, felspathic granite; potash greensand, a greensand yielding potash; potash kettle, a large vessel employed in the manufacture of potash; potash-lime, see quot.; potash-mica, a silicate of aluminium and potassium = muscovite; potash-water, an aerated beverage; water impregnated with carbonic acid gas, to which is added potassium bicarbonate.
1839Ure Dict. Arts 39 If *potash alum is to be formed, this sulphate of alumina is evaporated to the specific gravity of 1·38.
1862Dana Man. Geol. §55. 55 One [species of feldspar] has in addition potash and is a *potash-feldspar. Ibid. 56 Orthoclase or potash-feldspar.
1845Darwin Voy. Nat. xv. (1873) 320 Grand bare pinnacles of a red *potash-granite.
1868Rep. U.S. Comm. Agric. 402 Calcareous Marls and *Potash Greensands.
a1817T. Dwight Trav. New Eng. (1821) II. 256 The method of making potash in those large vessels,..now known [as] *potash kettles.
1866Watts Dict. Chem. IV. 692 *Potash-lime, a mixture of hydrate of potassium and quicklime.
1839–47Todd's Cycl. Anat. III. 816/2 The *potash-ley will now gradually recede into the large bulb.
1865Watts Dict. Chem. III. 1011 Chemically, micas may be divided into *potash-micas, containing little or no magnesia..; and magnesia-micas.
1764Museum Rust. II. xcviii. 327 The ashes, which are called *pot-ash muck, make excellent manure for some kinds of soil.
1874Garrod & Baxter Mat. Med. (1880) 123 Experiments..have shown that the *potash salts, when introduced immediately into the blood, are extremely poisonous.
1899Allbutt's Syst. Med. VIII. 861 To scrape the nail thin, and then after softening it with *potash soap, to apply chrysarobin.
1802W. Saunders in Med. & Phys. Jrnl. VIII. 492 [N. Paul] has introduced also the gaseous *pot-ash waters.
Hence ˈpotash v., trans. to treat or manure with potash; poˈtashery [cf. colliery, pottery], a factory where potash is made; pl. potash-works.
1799Canada Constellation (Niagara, Ontario) 8 Nov. 4/1 For field ashes, 9d. at the potashery, and 6d. if he goes for them. 1846G. Warburton Hochelaga I. 263 Potasheries, tanneries, breweries, iron-works, paper-works, and others. 1860Emerson Cond. Life, Power Wks. (Bohn) II. 332 Whether to whitewash or to potash, or to prune. 1882W. M. Thayer From Log-Cabin to White House 150 A pot-ashery was an establishment containing vats for leeching ashes, and large kettles for boiling the lye. 1930Canad. Hist. Rev. XI. 39 The only buildings were..two saw-mills, a carding shop, a potashery, [etc.]. 1979Jrnl. R. Soc. Arts Dec. 60/2 A syndicate of Liverpool-Manchester merchants..opened potasheries in New York and Philadelphia. |