﻿156 Intelligence and Miscellaneous Articles. 



was at once referred by Mr. Salter to the Steganodictyum of M'Coy ; 

 and on further research he concluded that M'Coy's supposed sponge 

 is actually the cephalic plate of a Pteraspidian fish. The author 

 fully endorsed Mr. Salter's determination, and inferred that the 

 specimens of Steganodictyum Carteri are really head-plates of true 

 Cephalaspis. 



18. " On the Geological peculiarities of that part of Central Ger- 

 many known as the Saxon Switzerland." By the late Capt. James 

 Clark. 



The author described in detail the rocks of which the district 

 under consideration is composed, namely: — 1, the Upper Quader 

 Sandstone ; 2, Planer Limestone ; 3, Planer Marl ; 4, Lower Quader 

 Sandstone ; and gave a list of their chief fossils. 



The peculiarities of this region consist, first, in the abrupt and 

 marked variations of altitude without any corresponding inclination 

 or dislocation of the strata ; secondly, in the remarkable regularity 

 of the fissures by which the rocks are divided, which cross them at 

 right angles ; thirdly, in the phenomena observable along the 

 line of separation between the Quader and the Lusatian granite, 

 the Quader being overlain by the granite and syenite ; fourthly, in 

 the disposition of the basalt, which rises through the granite and 

 the stratified rocks above, indurating the latter, but not contorting 

 them. 



XXI. Intelligence and Miscellaneous Articles. 



ON THE TEMPERATURE OF FLAMES AND DISSOCIATION. 

 BY E. VICAIRE. 



DURING the combustion of a gaseous mixture in an enclosure 

 which is impermeable to heat, the heat evolved is employed 

 solely in heating the mass, and we may easily calculate the tempe- 

 rature which it will have attained after the combustion of a certain 

 fraction of the combustible element. 



Supposing this combustion to be complete, we obtain the ordinary 

 formulae of the temperatures of combustion. But these formulae 

 furnish results far higher than the temperatures which are actually 

 observed, and the beautiful investigations of M. H. Sainte-Claire 

 Deville clearly show us the reason of this ; it is, that after a certain 

 point the elevation of the temperature places anobstacle in the way 

 of a more complete combustion, because no combination can take 

 place without causing a dissociation which exactly compensates it. 



If we have determined the temperature by experiment, we easily 

 deduce from it the quantity of gas that has been burnt, by the same 

 equation which, if we knew the quantity burnt, would give the tem- 

 perature. 



But this equation, which I establish in a rather more general 

 manner than has hitherto been done, does not take the place of the 

 old formulas of combustion : it does not allow us to foresee the tem- 





