CHEMICAL N0I;ES.— GENERAL. 



By Thos. Steel. 



(Plate 1.) 



[Read 27th September, 1922.] 



1. Some Ferruginous Concretionis. 



Concretionary accumulations, siliceous and calcareous, are of common oc- 

 currence and have been frequently described, but similar deposits of a ferruginous 

 nature are not so frequently met with and I do not recall having noticed any re- 

 ferences to the chemical examination of such. Two somewhat interesting 

 examples of this class of concretion have come under my notice. 



Ferruginous stalagmites. — In a small grotto at Wentworth Falls, N.S. Wales, 

 near the railway station, known as Fairy Dell, water impregnated with ferrous 

 carbonate exudes from the sandstone roof and, meeting with atmospheric oxygen, 

 the ferrous salt is oxidised with liberation of carbon dioxide and deposition of 

 hydrated ferric oxide. The deposited oxide, together with silica and a little lime 

 and magnesia as silicates, takes the form of stalactites and stalagmitic masses. 

 The analysis below gives the composition of the latter. Plate 1., fig. 1, represents 

 a piece of stalagmite with its smooth outer surface, and fig. 2 the fractured end 

 exposing the numerous thin layers of which the mass is built up. 



F.erruginous Concretions. — At the foot of Cranky's Creek Falls, a small 

 waterfall near Fitzroy Falls, N.S. Wales, at a spot where a fairly liberal out- 

 flow of similar chalybite water occurs, the water forms a shallow pool in which 

 twigs and other objects, kept in motion by the running water, have become evenly 

 coated with ferric oxide. Some of the twigs (PI. 1., fig. 3) look like pieces of 

 surgical bougies, being smooth and rounded at the ends, while others have ir- 

 regular outlines due to the shape of the twigs. Fig. 4 represents a twig with a 

 very uniform thick coating. Outwardly it bears a striking resemblance to a 

 piece of stick liquorice. The wooden core is hard and stained deep brown and 

 looks just like a piece of wire. The pieces in fig. 5 are of a similar character to 

 the last. Fig. 6 is a fruit of Hakea dactyloides. There is also (fig. 7) a piece 

 of deposit showing a well preserved leaf of another species of Halcea which Mr. 

 H. Deane considers may be H. saligna. I have to thank Mr. Deane for his 

 kindness in going to a good deal of trouble to identify these specimens for me- 

 Owing to the thickness of the deposit on the fruit as figured it was quite im- 



