iy 
HOT SPRINGS in ICELAND. -Igt 
of various colours, and beautifully veined, refembling a va- 
riegated jafper. The heat may poffibly proceed from a fer- 
mentation of the materials compofing thefe mounds ; but more 
probably (I fhould conjecture) from the fprings and {team forced 
up through them. The fprings muft have acquired their heat 
at fome greater depth, from fome conftant, fteady caufe, (how- 
ever difficult to explain), adequate to the length of time they 
have been known to exift, with the fame unvaried force and 
temperature. 
Srprincs do not boil on or near thefe banks only. They 
rife in every part of the valley, and within the circumference of a 
mile and an half, more than an hundred might eafily be counted. 
Moft of them are very fmall, and may be juft perceived fim- 
mering in the hole from whence the fteam is iffuing. This, 
trailing on the ground, depofits in fome places a thin coat of 
fulphur. The proportion varies ; for near fome of thefe fmall 
{prings, fcarce any is perceptible, whilft the channels by which 
the water efcapes from others, are entirely lined with it for fe- 
veral yards. Neither the water, nor the fteam from ‘the larger 
{prings, ever appear to depofit the fmalleft proportion of ful- 
phur ; nor can the fulphureous vapour they contain be difco- 
vered, otherwife than by the tafte of what has been boiled in 
them for a long time. 
Many fprings boil in great caldrons or Bafons, of two, three 
or four feet diameter. The water in thefe is agitated with a 
violent ebullition, and vaft clouds of fteam fly off from its 
furface. Several little ftreams are formed by the water which 
efcapes from the bafons; and as thefe retain their heat for a 
confiderable way, no little caution is required to, walk among 
them with fafety. 
Tue thermometer conftantly rofe in thefe {prings to the 212th 
degree; and in one fmall opening, from whence a quantity of 
fteam iffued with great impetuofity, Dr Wricut obferved the 
“mercury rife, in two fucceflive trials, to the 213th degree. 
Re2 , [ 
