216 



Tartaric A cid =04 H2 O5 + HO, Occurs rather frequently, 

 either in the free state or half or completely saturated, especially 

 in sour, unmatured, and in sweet berries (for instance, in grapes) ; 

 in small quantity in roots, barks, woods, herbage, and abundantly 

 in Lycopodium com})lanatum, and proljably to be found in most 

 allied })lants. From the aqueous extracts of vegetable substances 

 it always passes into the deposit produced by acetate of lead, and 

 into the liquid that results, after the deposit has been decomposed 

 by sulphuret of hydrogen, and from which it may be obtained in 

 crystals by slow evaporation. The deposit of lead, should it con- 

 tain no othei" acid, may be used for its quantitative determination by 

 drying at 100° and weighing. In 100 parts, are contained 37.08 

 parts acid. The jjure acid crystallises in colourless, klinorhombic 

 ])risms and pyramids, is inodorous, of a pure and strongly acid 

 taste, fuses at 170" and becomes carbonised with the odour of 

 burnt sugar, dissolves in 2 parts cold and in 1 part hot watei', 

 also readily in alcohol, in 36 ])arts ether. The aqueous solution 

 yields with lime-water a deposit soluble in sal-ammoniac. With 

 jiotash, it forms tartar. The Tartai'ates of the true alkalies are in 

 the neutral state readily soluble in water, the acid ones only 

 sparingly ; the neutral Tartarates of most of the other bases are 

 si)aringly, or not, soluble in water, but soluble in tartaric and in 

 hydrochloric or in nitiic acids. All Tartarates dissolve in liquor 

 of ammonia and in the hydrates of potash and of soda, with the 

 exception of Tartarate of silver, which does not dissolve in the 

 latter two liquids, and of Tartarate of mercury, which does not 

 dissolve in any of the three. 



Taxill. Alkaloid of the leaves of Taxus baccata, prepared ac- 

 cording to Stas' method of the forensic investigation of alkaloids. 

 — A white, loose, amorphous powder, very bitter, slowly soluble 

 in water, readily in alcohol and in ether, fusible to a yellow resin 

 by a gentle heat ; also soluble in diluted acids, the solutions of 

 which yield no crystals. Precipitable by caustic alkalies, tannic 

 acid, tincture of iodine, not 1)y chloride of platinum. Concentrated 

 sulphui'ic acid effects a purple red solution which becomes decolor- 

 ised by water. 



Tlialloclllor. The green pigment of Cetraria islandica. Exists 

 in the ether, containing oil of rosemary, used for washing the 

 cetraric acid (see this). Evaporate to dryness the solution, re- 

 maining after the ceti-aric acid has been removed by crystallisation, 

 dissolve the remnant in boiling alcohol, dilute the alcohol with 

 water until of a strength of about 42°/^ and hlter boiling hot. 

 Repeat this several times, in order to remove lichestearic acid, 

 and draw out the di'ied remnant with petroleimi. Thallochlor 

 and fat are dissolved, while cetraric acid and brown substances 

 remain behind. Submit the sohition to distillation under addition 



