1814.] Mr. IVilBams, the Mineralogist. S3 



•' coals, and iheir concomitant strata,"' occur in basin-shaped coal- 

 fields which are unconnected with each other; thus making a 

 remarkable approach towards distinguishing the Independent Coal 

 Formation of the justly celebrated Piofessor at Freyberg. The 

 opinion that beds of tuhinstone (meaning chiefly greenstone and 

 basalt) are unerupied lavas bad gained ground in Scotland, being 

 supported especially by the late ingenious Dr. Hutton : Mr. Wil- 

 liams, however, shows, that " basaltic strata spread as wide, and 

 stretch as far in the longitudinal line of bearing, as any concomitant 

 strata, being regularly placed among the others which form the 

 solid superficies of our globe; — they have therefore been formed in 

 the same way as the other strata : — the columnar and glebous 

 figures which they sometimes exhibit have happened from drying; — 

 and it would be strangely absurd to imagine that burning lava could 

 come in contact witii coal without destroying it."* Besides, this 

 essay on the mineral kingdom contains much valuable practical 

 information, particularly on the interesting subject of coal-mining; 

 while some unsupported speculations, concerning " the mutations 

 of our globe," and similar topics, in which the author has chosen 

 occasionally to indulge, can very easily be forgiven. 



Article II. 



On the Dallnnian Theory of Definite Proportions in Chemical 

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



(Continued from p. 18.) 



Though only a year has elapsed since the publication of my 

 essay on the weight of the atoms of chemical bodies in the second 

 volume of the Annals of Philosophy, p. 32, so much additional 

 information has been thrown upon the subject, partly by Dr. Wol- 

 la-ton's table to be published in the Philosophical Transactions for 

 1814, -.md partly from the great number of new analyses contained 

 in Professor Her/elius' truly valuable paper on the cause of chemi- 

 cal proportions inserted iii the second and third volumes of the 

 Annals of Philosophy, that 1 already conceive it to be proper to 

 point out the alterations which must be made in the table of atoms 

 given by me (Annals of Philosophy, vol. ii. p. 42,) in order to 

 rendci it a fair representation of the present statu of our knowledge. 

 1 have my elf made a few experiments in order to elucidate some 



' Ml il K mi • loin, vol. ii. (id. 48. tee, i ttUo Introduction, p. \liii. where 



iied own. uk ure Introduced on lite Hutioniao Theory, which U*l beeu 



thru tu .-. '•• an., .i i. 



j 2 



