54 REPORT — 1851. 



where expensive batteries have to be constantly kept charged, although but seldom 

 used, these batteries would be found to possess great advantages, as they would be in 

 action, only when required, by a momentary immersion into dilute acid. 



This battery likewise possesses surprising magnetic and odylic power, for its size ; 

 but these applications of it still afford ample scope for further investigation and 

 research. 



On the Constitution of Salts. By Professor A. W. Williamson. 



Chemists have of late years considerably extended the meaning of the term salt ; 

 acids and bases are now rather viewed as acid salts and basic salts respectively, than as 

 compounds of fundamentally different arrangement, and there seems reason to believe 

 that the molecular structure of the so-called simple bodies is analogous to that of salts. 

 Thus any view which best explains the properties of salts may be expected to apply 

 ultimately to the molecular structure of matter in general. 



It was remarked that a serious error had crept into chemical science by the intro- 

 duction of a different unit of comparison in organic chemistry to that which is em- 

 ployed in the inorganic department of the science. The removal of this error and 

 ?,doption of an uniform standard of comparison, naturally leads to viewing chemical 

 action as consisting in substitutions rather than in direct combinations. The best 

 studied processes of organic chemistry have been found to consist of double decompo- 

 sitions. Numerous other instances were mentioned, in which the result may be far 

 more simply explained by a process of double decomposition than by the supposition 

 of unknown predisposing affinities invented for each ; and various arguments were 

 adduced why the same mode of reasoning ought to be extended even to the simplest 

 phcenomena of inorganic action generally considered as mere combinations or sepa- 

 rations. It was shown that water may be assumed as a very general if not universal 

 type and standard of comparison, by viewing other bodies as formed from it by the 

 replacement of one or more atoms of hydrogen in water by their equivalent of various 

 simple or compound radicals. The atom of radical thus replacing hydrogen is some- 

 times equivalent to one atom of that element ; in other cases it is equivalent to two. 

 The difference between monobasic acids, such as nitric and bibasic acids as sulphuric, 

 were shown to follow as a necessary consequence of such a difference of the respective 

 radicals NOo and SO,. 



GEOLOGY AND PHYSICAL GEOGRAPHY. 



On the probable Dimensions of the great Shark (Carcharias megalodon) of the 

 Bed Crag. By J. S. Bowerbank. F.B.S. 



The teeth of this fish are common in the coprolite beds of Suffolk ; but although 

 exceedingly hard, they are usually much water- worn, and have nearly always lost the 

 serrated edges which are so well preserved in specimens of the same species from 

 Malta. The teeth of the upper jaw may be known from the lower teeth by their 

 comparative narrowness and thickness ; those from the sides of the jaws are progress- 

 ively smaller and shorter. The largest specimens measure from 'i\ to 5 inches in 

 length. In order to give some idea of the magnitude of the creature to which they 

 belonged, Mr. Bowerbank exhibited the jaws of the largest known specimen of the 

 Carcharias glaucus of Australia; it was killed by a whaling crew, at Port Fairy, Au- 

 stralia. It measured 37 feet in length ; its vertical gape is 25^ inches, its horizontal 

 20-3- inches ; the length of its largest teeth 2f inches. From the measurements it is 

 inferred that the fossil shark must have had a gape of at least 3 feet by 4, and an entire 

 length of not less than 65 feet. This estimate is not at all improbable, as there exists 

 a (comparatively harmless) species — the Basking Shark — in the British seas, of which 

 one individual, killed off Brighton, measured 36 feet, and one which was stranded in 

 the Orkneys, and described as a " sea-serpent," exceeded 50 feet in length. Looking 

 at the mineral character of these fossils, and their association with the teeth of a second 

 Maltese shark {Oxyrrhina hastalis), not found either in the London clay or coralline 

 crag, Mr. Bowerbank was inclined to regard them as having been derived from the 



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