Buarr.—On the Building Materials of Otago. 141 
The ordinary English building stone which most resembles this is the 
Kelton Oolite, its analysis being— 
Carbonate of lime ... ssi ay 92.17 
“magnesia ‘o eh 4,10 
Iron ae alumina ... Ss ss .90 
Water and loss He ae ak 2.83 
100.00 
The weight of Oamaru stone, wet from the quarry, is 105 pounds, per 
cubic foot, and, when perfectly dry, 92 pounds; that of the Kelton Oolite, 
when dry, 128 pounds. The lightest limestone in England is the Bath 
Oolite, which weighs 115 pounds per cubic foot. The New Zealand product 
is, therefore, the lightest by about 23 pounds per cubic foot. 
Applying the chemical tests to the Oamaru stone, we place it on a par 
with the Oolites and common limestones of England and the Caen stone of 
France. According to Dr. Hector, the resistance it offers to the disinteg- 
rating action of Glauber Salts is comparatively feeble. Its inferiority to the 
above mentioned stones consists chiefly in its excessive porosity. I have 
made several experiments, with the view of measuring its absorbent powers, 
the results of which are worth recording; A block of Kakaunui stone, used 
as a footstool in my office since 1868, and consequently thoroughly dry and 
hard, furnished the best possible materials for the tests. A piece of this 
stone, seven inches square and one and a half inches thick, equal to 73.5 
cubic inches, weighing, when dry, 56 ozs. 17 dwts. 11 grs. troy, was put in 
water ; within 40 hours it had absorbed 12 ozs. 15 grs., equal to 81 per 
cent. of its entire bulk, and 21 per cent. of its weight. The specimen was 
allowed to remain in the water for sixteen days, when the quantity absorbed 
had increased to 14 ozs. 2 dwts. 19 grs., which gives 86 per cent. of the 
entire bulk, or 228 gallons of water in a cottage wall ten feet square and one 
foot thick. 
A bar of Oamaru stone, 18 inches long and 1.65 inches square, was 
next placed vertically in a glass of coloured water ; it stood 3.2 inches into 
the liquid. In six hours the moisture was quite visible to the top of the 
bar, and in twelve hours the colouring matter had risen 7} inches. As 
the stone in both these experiments was particularly dry, the maximum 
results are probably obtained ; but, on the other hand, the vertical position 
of the bar, in the second ekverthicht. was less favourable to the absorption of 
moisture than that usually occupied by stones in a building, particularly 
the horizontal parts of mouldings, cornices, copings, and window cills. It 
should be pointed out that the Oamaru stone absorbs 36 per cent. of its 
bulk without pressure, while the most porous English stone only absorbs 
