APPENDIX 



Notes OIL some Vegetable Exitdatlons. 

 By J. H. BIAIDEN, F.L.S. 



Professor Tato lias placed in my liaiuls for exaiiiiiiatioii, the Vegetable. 

 Exudations collected during the Horn Expedition. The samples were quite 

 small, and an exhaustive examination of most of them was therefore out of the 

 question, but they are of scientific interest, particularly in view of our scanty 

 knowledge of authentic substances of this character, especially from the interior of 

 the continent. The collection of such substances in the interior nuist necessarily 

 be a slow process, as the gums are washed oil' the trees Ijy the first shower of rain, 

 the astringent exudations are affected both by the rain and by the fierce rays of 

 the sun which induce changes in their C(jmposition, while the resins readily dry up, 

 become brittle, fall to the ground and are lost. 



No. 1. " Portion of an ant's nest, consi.sting of sand agglutinated by gum 

 from Triodia pi/iigens, formed around the base of the grass, and continued as 

 cylinders around leaves and Hower stalks. Tempe Downs." This substance has 

 the appearance of a lump of reddisii-brown clinker. When treated at a very low 

 temperature the resin melts (even in the flame of a match), and in its crude state 

 would make a useful cement. When the resin has burned away, the residue 

 consists of sanrl, pi-incipally (juartz coated with ferric oxide, the latter bcnig 

 removed by dilute hydrochloric acid. This ferric oxide assists to give the original 

 mass its reddish-brown appearance. When the original substance is treated with 

 alcohol (rectified spirit), the resin readily dissolves, leaving the sand, which differs 

 in no way from that obtained by burning off thi^ resin. Ether dissolves the 

 greater portion of the resin, l>ut instead of the residunl resin being dark brown as 

 ill the case when alcohol is used, it is of a g(jlden yellowish colour, and when 

 ignited Ijurns away without residue, while that portion extracted by alcohol after 

 the ethereal extract has been removed, leaves a small (juantity of residue. 



The bright yellow re.sin melts at 83° C The oi'iginal resin extracted by 

 alcohol melts at 110° C, while the alcoholic residue h^ft (»n I'cmoval of the resin 

 st)luble in ether does not melt at 110° C It consists partly of inorganic 

 material. As it was present in small (|uantities, its composition could nut Ije 



