202 BUILDING STONES OF ST. JOHN's CATHEDRAL, BRISBANE 



The Specific Gravity. 



The specific gravity of the stone used in the Govern- 

 ment Printing Office was 2*337, and the absorption by weight 

 4-41 %, giving a bulk absorption of 1X3-30 %. 



Subjected to acid tests, the stone, after being immersed 

 in a solution containing 2J % hydrochloric and 2J % 

 sulphuric acids for 48 hours' was quite friable after the 

 treatment. 



Chemically, the stone is stable, and contains a medium 

 silica percentage, while the loss on ignition and ferric oxide 

 values are higher, the latter one would expect from the 

 colour of the stone ; lime and magnesia are absent or present 

 in slight traces only. 



The above results carried out for the Public Works 

 Department on the brown stone obtained from Wright's 

 quarry for the Government Printing OflFxe now being 

 erected, might be taken in a general way to hold for the 

 brown stone from Wright's quarry in the Cathedral just 

 completed. 



The compression test is a fair one for sandstones, and 

 gives a value more than sufificiejit for the purposes to which 

 the material is put, being approximately the same as the 

 Sydney stone. 



The absorption value is medium, but in a climate like 

 Brisbane enjoys, and which is for building stone purposes 

 free from frost, it does not matter to any great extent, more 

 especially as the atmosphere of this city is not laden with 

 acids, and the stone shows no traces of carbonates. 



The chemical constitution and acid test call for little 

 comment. 



Reviewing the above tests, this stone for building 

 purposes must be regarded as a very fair building material 

 in comparison with other Australian sandstones. 



(3) Sydney Sandstone. 



This is one of the widely-used Sydney freestones, 

 and is obtained from the Pyrmont quarries, being known 

 there as the Purgatory stone. It is hard, according to 

 masons, as hard as its name, and has given evidence of its 

 weathering qualities in Sydney, where the conditions are 

 perhaps somewhat more severe than here. Its chief 

 objection has been the manner in which it frets in certain 



