BY J. H. MAIDEN. 37 



boi'ne in mind that vegetable substances of an injurious nature 

 {e.g., the poisonous principle in Macrozaviia seeds) are sometimes 

 not capable of detection by ordinary chemical processes. 



My sample has the appearance of an inferior gum arable ; it 

 breaks with a dull couchoidal fracture ; the colour varies from 

 amber to colourless. 



After 24 hours in cold water a portion of the gum remained 

 undissolved, and had swollen a good deal. After separating the 

 solution, this insoluble substance was treated with very dilute 

 potash ; it readily dissolved, and on acidifying with acetic acid 

 and adding alcohol, arabin was precipitated, showing the insoluble 

 portion to have been metarabin. The gum soluble in cold water 

 was proved to be arabin. The composition of this sample of gum 

 is :— 



Arabin 68-8 



Metarabin... ... ... ... 16"1 (by difference) 



Ash 2-0 



Water 13-1 



100 

 I have I'eceived (also from Mr. William Bauerlen, collector for 

 the Technological Museum) a sample of gum from Panax murrayi, 

 obtained from Lindendale, Lismore, where it is known locally as 

 " Pencil Cedar," and where it attains a height of 40-60 feet, and 

 a stem-diameter of 9 to 24 inches. It was collected in January, 

 1892, and was analysed a month later. 



This gum is brittle, like that of P. sambtocifolius, var. angusta, 

 and not viscous like that of P. elegans. Its taste is not pleasant ; 

 it has not much odour, not resembling P. elegans in this respect. 

 It is fairly light in colour, although portions are as dark as 

 ordinary glue. 



In cold water it wholly dissolves to a clear transparent liquid, 

 not opalescent like that of P. sambucifolius, var. The aqueous 

 solution has an odour different from that of the others, and not 

 so pleasant. It is difficult to describe. 



