Buarr.—On the Building Materials of Otago. 151 
scareely possible to get a well burnt brick in Otago, but latterly a consider- 
able improvement has been made in this respect. If the preparation and 
tempering of the materials were only brought to the same standard, there 
would be little cause for complaint. 
The Hoffenan, or German perpetual kiln, of which there is a sample at 
Hillside, burns bricks, lime, or cement, in. a very effectual manner, at a 
fabulously small outlay for fuel. The principle is simply the utilization of 
all the heat produced, which is done in a most ingenious manner. The air 
that feeds the fire passes through the cooling bricks, in doing which it cools 
them, and in exchange becomes heated, so as to act like a hot blast on the 
burning mass. Then the heated gases from the furnace are carried through 
successive stacks of unburnt bricks, by which means they are dried and 
rendered fit for the fire. The fuel used is dross, or dust from the Green 
Island lignite, and it is put into the furnace in homepathic doses with a 
trowel. 
An ordinary English brick, when perfectly dry, absorbs seven per cent. 
_ of its weight of water in fifteen minutes. I have made experiments to 
determine the absorbent property of the colonial article, and find that a 
hard red brick absorbs fourteen per cent., and a soft one thirteen and a-half 
per cent. of its weight in the same time. 
The fact of the soft brick having absorbed nearly as much as the hard 
one, is a clear proof that the inferiority of the colonial product is attributable 
more to the imperfect manner in which the raw materials have been pre- 
pared than to deficient burning in the kiln. 
The establishment of the pottery works at Tokomairiro, and the success 
which has attended them, proves in the most conclusive manner the exist- 
ence and practical utility of fire and pottery clays throughout the Province. 
The articles manufactured there require raw materials of the most varied 
kind, from refractory fire clays that resist the fiercest heat to the mixed 
varieties that melt at ordinary temperatures. Nearly all these clays are 
found in the railway cuttings between Tokomairiro and Clutha, and the 
establishment of the pottery may be traced directly to the construction of 
the railway, which revealed the existence of the raw materials in that neigh- 
‘bourhood. 
Although the bulk of the articles manufactured at an ordinary pottery 
have no connection with the building arts, there are many of its products 
that can be utilised. In addition to the common drain-pipes, chimney-pots, 
and tiles, we will soon want tesselated pavements for halls and hearths, and 
terra-cotta goods of all kinds for ornamental purposes. 
The raw materials for these articles exist in considerable quantities 
