104 ZYGOPHYLLE^. 



Description— The resin occurs in globular tears ^ an inch to 1 inch 

 in diameter, but much more commonly in the form of large compact 

 niRvSses, containing fragments of wood and bark. The resin is brittle, 

 breaking with a clean, glassy fracture; in thin pieces it is transparent 

 and appears of a greenish brown hue. The powder when fresh is 

 grey, but becomes green by exposure to light, and air. It has a slight 

 balsamic odour and but little taste, yet leaves an irritating sensation 

 in tlie throat. 



The resin has a sp. gr. of about 1'2. It fuses at 85° C, emitting a 

 peculiar odom* somewhat like that of benzoin. It is easily soluble hi 

 acetone, ether, alcohol, amylic alcohol, chloroform, creasote, caustic alka- 

 Hne sohitions, and oil of cloves ; but is not dissolved or only partially 

 by other volatile oils, benzol or bisulphide of carbon. By oxidizing 

 agents it acquires a fine blue colour, well shown when a fresh alcoholic 

 solution is allowed to dry up in a very thin layer and this is then 

 sprinkled with a dilute alcoholic solution of ferric chloride. Eeducin 

 agents of all kinds, and heat produce decoloration. An alcoholic solu- 

 tion may be thus blued and decolorized several times in succession, but 

 it loses at length its susceptibility. This remarkable property of 

 guaiacum was utilized by Schonbein in his well-known researches on 

 ozone. 





Chemical Composition— The composition of guaiacum resin >v 

 ascertained by Hadelich (1862) to be as follows :— 



as 



Guaiaconic Acid, 70-3 per ceni 



Guaiaretic Acid, . . , , . . . , Iq-o 



Guaiac Beta-resin, 

 Gum, 



99 



9-8 

 3*7 



Ash constituents, . . , '. ' ' ', ! 0"S ,9 



Guaiacic Acid, colouring njatter (Gnaiac yellow), and ) 

 impurities, ^ 



4-9 



If the mother liquor obtained in the preparation of the potassiuw 

 salt of guaiaretic acid {vide infra) is decomposed by hydrochloric acid, 

 and the precipitate washed with water, ether will extract from the mass 

 C.uai«t'o«^c JezV?, a compound discovered by Hadelich, having tlie 

 iS'n^ ^r? 0"- It is a light brown, amorphous substance, fusing at 

 iWU y It IS without acid reaction but decomposes alkaline carbonates- 

 tormin^ uncrystallizable salts easily soluble in water or alcohol. It }^ 

 insoluble 111 water, benzol, or bisulphide of carbon, but dissolves in 

 ether, chloroform, acetic acid or alcohol. With oxidizing agents it 

 acquires a transient blue tint 



Guaiaretic Acid, C^WQ\ discovered by Hlasiwetz in 1859,may be 



W-[r.£ /'''"' ^^' '^^^ ^^«^^ ^y alcoholic potash or by quick^^^;; 

 VV ith the former it produces a crystalline salt ; with the latter an amor 

 phous compound : from either the liquid, which contains chiefly a sa^ 

 ot ^laiacomc acid, may be easily dcclnted. Guaiaretic acid is obtain 



ed 

 d 



rL+!.ir-^'''i?'S one of the salts referred to with hydrochloric acid, ana 

 W.f S^^ T"" ^^^^^^^- The crystals, which are soluble also m eth i- 

 an^in-f '''^'"^'' *^^^^^^^ bisulpliide or acetic acid, but neither "^ 

 out7ecn J'"' •l'^ '''"^^^■' ^^^t ^^1^^ 80^ a, and may be volatihzed v^th 

 Bv TlF'''^^- ^^'^ ^^id i« ^^^ coloured blue by oxidizing agents- 

 sli.htTv v.^^^^^^^^ §^^^^^^™ ^^^«i^ ^^'ith boiling bisulphide of carbon 

 sli2:htly yellowis!^ solution is obtained (containing chiefly g^'^^^^'^^ 



