Clijton College Scientific Society. 79 



ABSTRACT 

 OF PAPER ON NODULES AND CONCRETIONS. 



These may be simply divided into nodules of infiltration and 

 nodules of concretion. 



The manner of formation of the first is similar to that of mineral 

 veins, they were probably deposited from solutions aided by electrical 

 currents. But it is apparently impossible satisfactorily to account for 

 the fractured and recemented state of many nodules. The most 

 beautiful of the commonest nodules of infiltration are the agates, 

 which consist of silica coloured with other oxides. 



Concretions, properly so called, are in many respects similar to 

 crystals. The mineral particles which form them seem to have had 

 sufficient freedom to move towards each other, while the medium 

 through which they were disseminated was too dense to allow them to 

 assume a crystalline form. In some clays we find crystals of gypsum 

 and calcareous nodules : the former were probably first formed. 



Again, we find tliat some concretions — as of calcite and pyrite — 

 are internally crystalline. 



The paper was illustrated by a large number of beautiful specimens 

 from the collections of the Society and of IMr. WoUaston. 



MEETING, February 26th, 1874. 

 The President in the Chair. 



The third meeting for the term was held in the Physical Lecture 

 Room. There were Twenty-eight members and visitors present. 



The President exhibited and described a large number of fossils 

 from Clifton. 



H. Moser read a paper upon " Salmonidoe." At the conclusion of 

 this paper, the President and G-. H. WoUaston, Esq., the Vice-Presi- 

 dent, made some remarks u])on the subject. 



On the proposal of R. M. Johnston, seconded by the President, 

 W. Becker, Esq., was elected an honorary member of the Society. 



The Meeting then adjourned. 



MEETING, March 26th, 1874. 

 The President in the Chair. 



The fourth meeting fur the term was held in the Chemical Lecture 

 Room. There were forty-six members and visitors present. 



The President exhibited some fossils. 



J. Swinburne then read a paper on " Combustion," which he illus- 

 trated by several very successful and effective experiments. 



The President made some remarks upon this paper at its close. 



R. M. Johnston had been announced to read a paper upon " Gas/' 

 but on account of the lateness of the hour it had to be postponed. 



The meeting then adjourned. 



