Building Materials. 27 
these causes, they undoubtedly have exercised an influence 
more powerful than we are at first inclined to admit. 
The Sandstone procured from Irrewarra, in the parish of 
Boroondara, singularly contrasts will other beds in the im- 
mediate vicinity. Though, as will be shown, it is neither so 
durable nor so valuable in other respects as the Geelong 
Sandstones, it is a proof that the changing character of the 
beds needs only to be noted and followed to lead to other 
deposits of a better description. 
The block which has been handed to me for examination 
is composed of coarse quartz grains, much water worn, 
agelutinated by an argillaceous and siliceous cement. Its 
shades vary from pale cream color to nearly pure white, and it 
is irregularly traversed by red and brown ferruginous streaks 
and spots. It yields readily to the hammer in the direction 
of its cleavage, as is usual with stones of this class. The 
average weight is 155 lbs. per cubic foot. Its capacity of 
absorption is so great that that alone is a sufficient reason for 
its rejection as a material for large buildings. After im- 
mersing a portion of the block, weighing 55°85 ozs. for 72 
hours it absorbed 3-043 per cent. by weight, and another 
experiment on a smaller piece gave 3°217 per cent. B 
simple immersion, allowing it to remain till air bubbles had 
ceased to escape, the results were as follows :— 
Experiment, No. 1, 2°542 per cent. 
” 2, 2-320 ” 
9 3, 2194 ” 
Thus, it only absorbs a large amount of water, but what 
speaks more strongly in its disfavor, such absorption is carried 
on very rapidly. 
This stone has been subjected to a variety of tests, some of 
which it isnecessary to particularize. A small specimen of 
the average quality was immersed ina solution of a carbonate 
till it had absorbed the maximum quantity ; it was then placed 
ina weak solution of acid: this gave rise to brisk effervescence, 
and frequent repetitions of this resulted in the destruction of 
the surface of the stone. This test I have found valuable in 
practice: it is needless to state that it can only be used when 
the cement is not of a calcareous nature. 
Another series of tests were instituted by immersing the 
stones in solutions of various salts, and then suspending it over 
the vessel containing the fluid. After this process was many 
times repeated the salt re-crystalized in the stone; and the 
