149 



of Coorongite made at his request by Dr. Bernays, he points out 

 that " any residue left by a Cryptogam (assuming of course that 

 no extensive change of composition had taken place in it, except 

 the loss of water) " would have a considerably different chemical 

 composition, and for this reason inclines to regard the substance 

 as of mineral origin, and being derived from an oily matter which 

 originally floated on the surface of the water. 



In an article on the same subject J. R. Jackson* quotes the 

 observations of G. Francis, who concluded that Coorongite was in 

 all probability a vegetable production, and on chemical examina- 

 tion found it to be " resolvable into two educts : (1) soft semi- 

 fluid, like a balsam . . . and, except in its semi-fluidity, 

 resembling vegetable wax " ; and " (2) a tough pulverulent sub- 

 stance," apparently a " modified form of cellulose associated, but 

 not chemically combined, with the first described educt." 



Some further information relating to the occurrence and 

 Lormation of Coorongite may be quoted from the correspondence 

 on the subject in the years 1866 and 1867. The substance 

 accumulates on the surface of the flood waters, which form a 

 shallow swamp in the winter but recede annually, leaving it on 

 the soil, so that it can be collected in summer when the ground is 

 hard* In some places where the deposit was destroyed by fire 

 one summer, it was again found covering the ground in the 

 following summer. In one locality, when the deposit was re- 

 moved from the surface of the ground, other layers were found 

 buried in the sand beneath it. 



In 1903 Cummingt made chemical analyses of Coorongite and 

 gained some further knowledge of the composition of this sub- 

 stance. He found that, besides the ash, two constituents were 

 present, one of them being a wax-like solid which can be 

 extracted with carbon-disulphide ; the other is insoluble In 

 carbon-disulphide, but can be saponified by hot alcoholic solution 

 of caustic potash, forming a soluble soap. For the soluble con- 

 stituent of Coorongite he obtains the formula (Ci H 18 O) x , with 

 x probably equalling 8, and for the other constituent CioH 2u 3 , 

 the figures given by the analyses being as follows : 



Soluble Constituent. Insoluble Constituent. 



Carbon 77-91 64'22 



Hydrogen 11*92 J 0*52 



Oxygen 10-17 25*26 



Cumming suggests that the insoluble constituent may have been 

 derived from the soluble one by hydration and oxidation. 



On examining samples of Coorongite in the Museum at Kew, 

 I found that this substance bears a distinct resemblance to 

 N'hangellite. There is a yellowish matrix which, though much 

 more generally structureless than in the other case, shows an Alga 



* J. R. Jackson, Coorongite or Mineral Caoutchouc of South Australia (Pharm* 

 Journ. and Trans., 1872, pp. 763-4 and 785). 



t Cumming, Coorongite, a South Australian Elaterite, "Chemical News," 

 vol. 87 (1903), p. 306. 



