XX. ABSTRACT OF PROCEEDINGS. 



a shark, or else a coprolite, but it is usually considered to 

 be of vegetable origin. Remarks were made by Professor 

 David. 



3. " On two new Grass Smuts," by Ewen MacKinnon, 



B.Sc 



Remarks were made by Mr. Maiden. 



exhibits : 



1. A hydrous aluminium phosphate from Reservoir Hill, 

 Murwillumbah, by Professor David. It is abundant, and 

 the impure mineral is used for road making. 



2. Experiments witli colloidal solutions or silicic acid 

 gels, by Mr. W. J. Clunies Ross. These exhibits illustrate 

 the various ways in which gels of silicic acid may be 

 obtained from water glass, silicate of soda, by means of 

 hydrochloric acid : 



First, coloured gels. Crystals of salts are dropped 

 into a solution of water glass, and allowed to grow. 

 The solution is then partly poured off, and HOI added. 

 With dilute HOI an opaque gel is formed. With excess 

 of concentrated HOI a clear gel, the growth becoming 

 white and the gel coloured, if from coloured salts. 



Second, solution of water glass taken, chloride of 

 gold added. Then the solution converted to gel by 

 hydrochloric acid. Solutions of various reducing agents 

 poured on to gel. Result shewn, after about a fort- 

 night. 

 Remarks were made by Mr. Hamlet. 



3. Miscellaneous botanical exhibits, by Mr. J. H. Maiden. 



(a) White Pine fruits (Callitris robusta) from the 

 Gunnedah district, which had been attacked by green 

 leek parrots for their seeds, and thus a scarcity of 

 seedlings had been caused. 



