in the Island St Michael.: - SOT 
time porphyritic. Each piece is composed of angular portions, 
apparently fragments, which are united by a yellowish-white 
siliceous substance, approaching in some respects to calcedony. 
It is hard and opaque, and has somewhat of a waxy lustre.. 
The cavities on which the amygdaloidal character of this rock 
depends, contain a small quantity of mealy and radiated zeo- 
lite. 
The hot-springs are situate towards one extremity of the 
valley, beyond a few cottages composing the village of Eurnas. 
They are not seen at any distance, being surrounded by small 
hills, some of which, there is great reason to believe, owe their 
origin in part, if not altogether, to the springs themselves. 
They are generally covered with short shrubs, but some of 
them are wholly devoid of any traces of vegetation. They are 
composed of clay of different degrees of compactness, which is 
variously, and often beautifully coloured by iron, under diffe- 
rent degrees of oxidation. The clay is intermixed with fine 
pumice and masses of siliceous sinter. As we pass along the 
narrow road from the village to this spot, the gradual change 
from a fertile to a barren soil is observed, and within a few 
yards of the hot-springs, nearly ail traces of vegetation are lost. 
At the extremity of the road the ground is almost snow-white, 
and then acquires a reddish tinge ; this increases in intensity 
and brightness, and finally passes through an infinite variety of 
shades to a deep brown. Here and there, patches and veins of 
a bright yellow and purple colour, add to the singular aspect of 
this remarkable spot. The clay is in some places so much in- 
durated as to retain an imperfect slaty character, but most of it 
is soft, and has an earthy aspect. It does not feel perfectly 
smooth when rubbed, but is full of hard grains, which are ex- 
ceedingly minute ; and when a mass of it is diffused in water, 
a quantity of fine siliceous particles is separated. It has many 
of the characters of tripoli. It is used by the peasants as an 
external application for cutaneous diseases, and is undoubtedly 
beneficial in some particular cases, from the quantity of sulphur 
it contains. Large pieces of siliceous sinter, of a grey colour, 
are imbedded in it, and it is covered in some parts by the same 
substance, which has accumulated upon it in layers, from an 
eighth of an inch to an inch in thickness. Near the extren^ity 
