26 Building Materials. i 
the minimum 164 lbs. It does not absorb so much water as 
might be supposed from its structure. After immersing an 
average specimen for 96 hours its increment in weight 
was 1°751 per cent.; anda mean of various experiments 
made on stones procured from the neighbouring quarries 
approach very nearly to this result. Were it not that 
this stone was exceedingly costly, both in obtaining it from 
the quarry, and inall its subsequent stages, it would be used 
in this Colony in preference even to granite. 
In addition to its value asa building stone, it is quarried for 
road metal and kerbstones, for which it is peculiarly adapted, 
and that is perhaps the best proof of its durability. 
The styles of architecture adopted in Melbourne, where 
Basalt is used, are not generally favorable to its appearance ; 
where it has received some degree of finish it is extremely 
handsome, and it is to be regretted that it has not been 
chosen for our public buildings. 
Basalt may be advantageously employed in the composition 
of mortar. When it is calcined and reduced to powder, it 
imparts to the cement the property of hardening under water. 
SANDSTONE. 
The Sandstones which I have examined are by no means 
favorable specimens of the formation which they represent. 
In general they have been procured at or very near the surface,’ 
and from the quality and properties of such specimens very. 
erroneous opinions have been formed of their nature. 
In the older formations, and here I would allude to an age 
antecedent to the Carboniferous era, it must be remembered 
that the surface of the strata has been exposed for countless 
ages to incessant changes; and the alterations which it has 
undergone will extend to various depths in exact proportion 
to the structure of the rock. 
The term “ metamorphic,” as used by geologists, is applied 
to rocks which have been altered by the effect of heat. Little 
attention has been paid to changes which take place by infil- 
tration, by the decomposing effects of air and water, and other 
causes, requiring lengthened periods of time for their com- 
pletion. 
Inclined strata, of a schistose structure, are more liable to 
such alteration than the comparatively undisturbed deposit of 
a coal basin; and though I am far from attributing the 
perishable nature of the Melbourne Sandstones wholly to 
