32 On the Daltonian Theory of [July, 



the river, we found some men working a quarry of greenstone. 

 This was not more than 50 or 60 yards from the din, and we 

 easily traced the greenstone to the lin ; at first we look it for a 

 vein ; hut on further examination at the bottom of the lin, 

 finding the rock there greenstone, and seeing large and thick 

 strata of slate clay, with some clay iron stone, alternating, and the 

 strata of these dipping eastward, and running below the green- 

 stone, we were both inclined to think it was a bed. From this 

 point to the shores of the Frith of Forth the country is entirely 

 composed of sandstone, limestone, slate clay, bituminous shale, 

 clay iron stone, coal, and various rocks of the floetz trap series. 

 Immediately on the shores of the Forth, these strata are in some 

 places covered with an alluvial deposite, which contains many 

 organic remains. These remains are in general of shells that 

 belong to species which at present inhabit the Frith of Forth. 

 Mr. Bald, in an excellent paper on the local fall of Alloa, 

 inserted in the Memoirs of the Wernerian Natural History 

 Society, enumerates the following species: — 



1. Ostraea edulis. 4. Turbo littoreus. 



2. Mytilus edulis. 5. Donax trunculus. 



3. Cardium edule. 6. Patella vulgata. 



Article IX. 



On the Daltonian Theory of Definite Proportions in Chemical 

 Combinations. By Thomas Thomson, M.D. F.R.S. 



I promised in an early number of the Annals of Philosophy 

 some observations on Mr, Dalton's theory of definite proportions, 

 and 1 now sit down to fulfil that promise. Too much attention 

 cannot be paid to this important theory, the developement of 

 which I consider as the greatest step which chemistry has yet 

 made as a science. It puts us in the way of establishing principles 

 of rigid accuracy as the foundation of our reasoning, and to call 

 in the assistance of mathematics to promote the pi ogress of a 

 science which has hitherto eluded the aid of that unrivalled 

 instrument of improvement. The idea of definite proportions 

 seems to have struck the miud of Richter, though the methods 

 which jie took to determine them were far from successful ; and 

 Mr. Higgins, in his work on phlogiston, maintained the opinion 

 that chemical bodies unite atom to atom. But the generalization 

 of the doctrine, and the striking and irresistible proofs deduced 

 from the combinations of the simple substances, and the acids 



