180 Henry C. liicJtards : 



TESTS. 



The following- investiirationRi were carried out on all the 

 sandstones : — 



1. To ascertain the specific gravity. 



'2. To ascertain the resistance to crushing. 



3. To ascertain the absorptive powers. 



4. To ascertain the resistance to corrosion. 



5. To ascertain the resistance to mineral acids. 



6. Microscopical examination. 



7. Chemical analysis. 



There are several other tests regularly conducted on building- 

 stones, but these were not included for various reasons, ^^^lile 

 a knowledge of the resistance to freezing is of supreme impor- 

 tance in many places, fortunately in Melbourne it is not so, as 

 this city is almost free from frost, also the difficulty of obtain- 

 ing anything like reliable results is very great. 



The resistance of a stone to abrasion by wind-blown particles 

 is rather important in Melbourne, but the difficulty of getting 

 reliable results and the lack of opportunity for carrying out 

 the test led to its non-inclusion. 



1. — S'jyerifir Gravity. 



Pieces of the stones were carefully dried at 110 degrees C, 

 weighed in air when cold, and then suspended in water and 

 there weighed. From fhe two weights the specific gravity was 

 determined. 



The s})ecific gravity is of value in indicating which stones are 

 liable to be the most absorptive, for with stones of the same 

 mineral composition the one with the highest specific gravity is 

 generally the least absorptive and so the most durable. 



Several determinations were carried out on each stone, and 

 the results a])pended below are the means of these. From the 

 specific gravities the Aveight per cubic foot of these stones has 

 been determined. With porous stones like these sandstones, the 

 determination of the true specific gravity is a matter of some 

 little difficulty, especially in obtaining the correct weight of the 

 stone when suspended in water. 



The Sydney stone has been inserted for comparison. 



