26 



Building Materials, 



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.; and a 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 in all its subsequent stages, it would be used 

 in this Colony in preference even to granite. 



In addition to its value as a 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 regTetted 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 



