172 ALEX. L. DU TOIT. 



by a sufficient rise in temperature and C0 3 would be 

 •evolved by the silication of limestones under the influence 

 of igneous sills and batholithic intrusions. 



Since, as will be shown later, there is strong evidence 

 that large basic or sub-basic masses were injected in Ter- 

 tiary times into the crust beneath the eastern part of the 

 Australian Continent, a likely source from which the balance 

 of the C0 2 and N over that derivable from the atmosphere 

 is at once provided. 



VII. The Rising of the Waters under Pressure. 

 Five main causes may act separately or in conjunction 

 to produce the flows from the Basin, the third of which has 

 not been considered worthy of citation hitherto: — 



(1) Gas Pressure. 



(2) Etock Pressure. 



(3) Contrasts in density due to temperature differences. 



(4) Hydraulic Pressure. 



(5) Thermal Sub-surface Springs. 



(1) Gas Pressure. — The influence of bubbles of gas in 

 raising the water to the surface has been considered an 

 important one by both Gregory and Symmonds, but this has 

 not been conceded by the Interstate Conference, although 

 the principle involved received recognition in their second 

 report (II, p. 16). 



The effect is directly calculable, and the results obtained 

 for different conditions are submitted in Appendix A, from 

 which it will be seen that the influence may be indeed con- 

 siderable, though the circumstances in Australia do not 

 appear to be such as to make it an important contributor 

 towards outflow as far as we know, except in some isolated 

 cases. 



The problem is a variant of that involved in the air-lift 

 pump (see Gibson, Hydraulics and its Application, London, 



