142 Transactions.—Miscellaneous. 
25 per cent., under a pressure of fourteen pounds on the square inch. It 
is doubtful, however, if an increase of pressure in the former case would 
give corresponding results, the stone being so excessively porous, gets 
completely saturated at once. When the dry samples were first put into 
water, the air rushing from the pores of the stone, caused bubbles to rise to 
the surface for fully ten minutes. The first experiment shews that the 
stone is capable of absorbing ten pounds per cubic foot more water than it 
contains when in the quarry, a result to me quite unexpected, and not 
easily explained. 
One of the most important points, in connection with the use of Oamaru 
stone, is the degree of induration it attains in drying, and the loss sustained 
by subsequent exposure to moisture. So far as the hardening is concerned, 
I am quite satisfied that the largest blocks used in ordimary masonry 
become equally hard throughout in a few months, and possibly im a few 
weeks, under the influence of a warm dry atmosphere. The hardness is not 
confined, as is sometimes supposed, to a thin crust on the surface of the 
stone, but penetrates to the centre, making the whole a perfectly homo- 
geneous mass. In consequence of the time required, I have not been able to 
prove by direct experiment that a stone once hardened becomes soft on 
exposure to wet. I fear, however, that such is the case; the window-sills 
and mouldings on the south side of the University building are now fully 
softer than when they left the quarry, and the chances are that these 
stones had acquired a considerable degree of hardness before being placed 
in the building. The cornice and parapet on Messrs. Dalgety, Nichols, 
and Co.’s warehouse, although in a much more favourable situation, on the 
sunny side of the street, is softer still; the stone can be scratched out in 
handfuls by the finger nails. This is, however, one of the oldest, if not 
actually the oldest piece of Oamaru stone masonry in Dunedin; it is, 
therefore, possible the material was bad to begin with. 
Against these unfavourable examples, the bridge in Thames Street, 
Oamaru, built in 1860, and several other buildings of the same age, in that 
locality, are not decayed, nor unduly charged with moisture. The ultimate 
durability of our Oamaru stone buildings cannot of course be determined at 
this early stage of their existence, and any estimate, short of actual trial, is 
little more than conjecture. Professor Black might, however, give us his 
opinion as to whether it can long resist the action of the saline breezes from 
the Ocean Beach, the sulphurous fumes of the Green Island coals, and the 
other impurities that are now so rapidly accumulating in the atmosphere of 
Dunedin. I should be loth to prophecy evil, but if the durability of the 
Oamaru stone is to be measured by its power of resisting moisture, it is to 
_ be feared that the handsome spires and facades that now ornament the city 
