IV. An Analysis of the Waters of Jome Hot Springs in 

 Iceland. By Joseph BlacK) M. D. ProfefJ'or of Me- 

 dicine and Chemijiry in the Univerfity of Edinburgh, Firjl 

 Phyfwian to his Majejiy for Scotland, Fellow of the Royal 

 College of Phyficians, and of the Royal Society of Edinburgh; 

 Member of the Academy of Sciences and of the Society of Me- 

 dicine of Paris , of the Imperial Academy of St Peter/burgh^ 

 &c. &c. 



f Read July 4. 1791 .] 



SIR Joseph Banks, to whofe indefatigable ardour for the 

 advancement of natural hiftory, the philofophical world 

 is fo much indebted, made a voyage to Iceland in the year 

 1772, to enquire into the productions of that remote part of 

 the world, and particularly into thofe of its famous volcano. 

 When he returned, he brought from thence, among many other 

 natural productions, fome petrified vegetables, and incrufta- 

 tions, formed by the waters of the boiling fprings ; and he was 

 fo good as to prefent a part of them to his friends here, who 

 were furprifed to find them compofed of filiceous earth. As 

 this was the firft example obferved, of water containing this 

 earth in fuch quantity as to form filiceous petrifactions, it raifed 

 a ftrong defire to have an opportunity of examining the water, 

 and of learning by what means this filiceous matter was dif- 

 folved in it ; and this opportunity was at laft given us by 

 John Thomas Stanley, Efq; who, excited by motives fimi- 

 lar to thofe of Sir Joseph Banks, equipped likewife a veffelj 

 and made a voyage to Iceland, during the fummer 1789. He 



brought 



