PREFACE. xxiii 



st the volcanic lava-currents V I had ever 

 isrfto rniv/ noij^nnoo rme 

 fince the year 1767, or ever fince my exa- 

 mination of the volcanic productions in 

 / i i ^-1 V133V? B ynnrn cU oloJ 

 Hefle, obferved the fame phenomenon ; and 



being convinced, by a variety of facts, that, 

 betides the falts and metals, many other fof- 

 fils receive a determined form by fufion and 

 cooling, as well as by their folution in aque- 



b' J T 



ous folvents; I was the more ilruck by this 



coinciding obfervation, and faw no reafon 



s<A n\ fcoHoi 11 -i \ /i -^l i; ? fl f ?fl y 



why thefe problematical rocks fhould not be 



. 'EpniifK 

 henceforth confidered as cryftallized lavas. 



Accordingly I communicated in 1769 an"acV 

 count of the prifmatical bafaltes at Felfoerg, 

 and other places in Hefie, to the Royal So- 

 ciety *; and, with fome further particulars, 



to Sir William Hamilton, and to the Royal 



j8r '^ 



3 



O ^ I 



Society m Gottingen 3 . 



If it deferves any praife, to have firft hit 

 upon a lucky hypothecs, it cannot poffibly 



be denied to Mr. Defmarejl ; and I may be 



..onn ; pi 



1 Explicat. des Planches de 1'Encyclop. liv:^VJt 

 Par. 1768. 



1 Philof. Tranf. TO!. LXI. and Ferber's Letter V. 

 3 German Memoirs of the Royal Society at Got- 

 i, Vol. I, 



b 3 allowed 



