litmus
(ˈlɪtməs)
Forms: 6 lyȝtmose, lyt(t)mos(se, litmouce, 7 litmas(e, -mouse, litt(i)mus, 7–8 litmose, 8 litmoss, lytmus, 7– litmus.
[Altered from MDu. leecmos, lijcmoes (mod.Du. lakmoes) lacmus, prob. from association with lit v.]
a. A blue colouring matter, obtained from various lichens, esp. archil, Roccella tinctoria. Also fig., as in litmus test.
It is turned red by acids, and the blue colour is restored by alkalis.
| 1502 Receipt for Corke in Arnolde's Chron. 71 b/1 Take an C. & a q'rt of lyȝtmose. 1518 Will of R. Hoby (Somerset Ho.), xij bagges of Lytmos otherwise called white Corke. 1546 Inv. Ch. Goods Surrey 107 Item for lyttmosse ijli. viijd. 1594 Plat Jewell-ho. iii. 37 Dry Litmas scraped in water. 1606 Peacham Art of Drawing 57 If you put to overmuch Litmose it maketh a deep blew. 1640 Rates in Noorthouck Lond. (1773) 838/2 Littimus, the cwt. qt. 112 lb. 1d. 1722 Act Encour. Silk Manuf. &c. in Lond. Gaz. No. 6040/7 Litmus the Hundred Weight,..twenty Shillings. 1811 A. T. Thomson Lond. Disp. (1818) 471 This solution..reddens tincture of litmus. 1898 Allbutt's Syst. Med. V. 448 Soak the papers in strong neutral litmus and dry them. 1957 Essays in Crit. VII. 80 Their possession is as good a cultural litmus test as any I can think of. 1971 Daily Tel. Nov. 13/2 The litmus test comes with the old issue of whether the NUS should re-join the IUS. 1972 Times 21 Nov. 21/7 The litmus test will be the effect of the rise from 4p to 10p in the basic charge for an inpayment. |
b. attrib., as
litmus colour,
litmus liquor,
litmus tincture;
litmus blue, a blue pigment prepared from litmus;
litmus paper, unsized paper stained blue with litmus, to be used as a test for acids; when reddened by an acid, it serves as a test for alkalis.
| 1612 Peacham Gentl. Exerc. 83 The principal blewes..are Blew bice, Smalt, *Litmose blew. 1727 W. Mather Yng. Man's Comp. 83 Put the quantity of a Hazel-Nut of Litmose-blue, to three Spoonfuls of Conduit-Water. |
| 1805 W. Saunders Min. Waters 30 Another portion of the same *litmus liquor reserved for comparison. |
| 1803 Davy in Phil. Trans. XCIII. 246 A fluid came over, which reddened *litmus-paper. 1827 Faraday Chem. Manip. xii. 270 Two of them [test papers]..surpass the rest, these are litmus and turmeric papers. |
| 1899 J. Cagney tr. Jaksch's Clin. Diagn. vii. (ed. 4) 367 May's *litmus tincture. |