167. CONIFERIN. 167 



Pinipicrm is described by Kawalier 1 as being freely soluble in 

 water and alcohol, insoluble in pure ether, and not precipitable by 

 basic acetate of lead. Its decomposition-products resemble those 

 of ericolin. 



Of glucosides which yield either fixed or difficultly volatile decom- 

 position-products not possessing any characteristic odour, the follow- 

 ing may be mentioned. 



Coniferin is sparingly dissolved by cold, but freely by warm 

 water and by alcohol. It crystallizes in glistening needles, and 

 melts at 185 (uncorr.). With cone, sulphuric acid it forms a 

 violet solution, and when moistened with hydrochloric acid and 

 phenol develops a blue colouration. Dilute acids resolve coni- 

 ferin into sugar and a resinous substance ; with emulsin it yields a 

 crystalline decomposition-product. The latter, which is sparingly 

 soluble in water and alcohol, can be removed by ether from its 

 aqueous solution. Its melting-point lies between 73 and 74. 

 Coniferin, when exposed to the air, gradually acquires a vanilla- 

 like odour, a change rapidly brought about by warming with 

 dilute sulphuric acid and bichromate of potassium, and caused by 

 the decomposition of the coniferin with the production first of the 

 methyl-ethyl ether of protocatechuic aldehyde, and finally of 

 vanillin' 2 ( 15,")). The reaction with hydrochloric acid and phenol 

 ma}- be used in testing for coniferin microcliemically in the cam- 

 bium of conifers. 



The identity of this substance with the coniferin of Tangel, 3 

 detected in sections of conifers by the red colouration produced 

 by cone, sulphuric acid and phenol, must be left for the present 

 an open question. Miiller 4 has shown that the hitter also occurs 

 in most indigenous trees (Salix, Populus, Prunus, Acer, Quercus, 

 etc.), and is to be met with in abundance, especially in the autumn, 

 in the hard bast and alburnum. According to Miiller, the phenol 

 only hastens the appearance of the red colour. 



Arbutin* is sparingly soluble in cold alcohol, ether, and cold 



1 Chem. Centralblatt, 705, 724, 1853. 



2 Compare Tiemann und Haarmann, Ber. d. d. chem. Ges. vii. 609, 1874 

 (Journ. Chem. Soc. xxvii. 895). See also Kubel, Journ. f. pract. Chem. 

 xcvii. 243, 1866. 



3 Flora, Ivii. Xo. 15, 1874. 



4 Ibid. No. 25. 



> Compare Kawalier, Chem. Centralblatt, 761, 1852 ; Strecker, Annal. d. 

 Chem. und Pharm. cvii. 288, cxviii. 292, 1861 ; Hlasiwetz and Habermann, 

 ibid, clxxvii, 334, 1875 (Journ. Chem. Soc. xxix. 78, xxx. 298). 



