Ponp.— Analyses of a few of the Fire-clays of Auckland. 349 
examination. For instance, Raglan, Coromandel, Wangarei, the Manukau, 
and many other parts of the country have sent clays competing for the 
foremost place for the purpose of fire-brick making, one notably from 
Taranaki, which was supposed to be very valuable for this purpose, proved 
on examination to be a silicate of magnesia, and formed a most delightful 
glazed surface at a high red heat, while at a whit®agat it was in a perfect 
state of fusion. But undoubtedly the Province possesses some excellent 
deposits of refractory clays; and some of these I now place before you. 
As the diagram will show, I have, for comparison, placed the celebrated 
Stourbridge clay first, as this has a world-wide reputation. Of the New 
Zealand, or at all events Auckland clays, I think the Waikato fire-clay 
has been the most noticed, and it has certainly deserved to be held in high 
estimation, for it is an excellent clay, but it must, I think, give place to the 
sample from the Miranda or Wharekawa coal seam. This latter, as will be 
seen, contains much less iron than the Waikato, and an entire absence of 
lime, which, in the other analyses, amounts to only a small per centage. 
The clay next in value is the Bay of Islands, but this, with a higher per 
centage of lime and iron, would not permit of so white a biscuit being made 
from it. One thing noticeable in the Waikato and Bay of Islands clays is 
the large amount of bituminous veins running through them, though 
entirely absent in the Miranda sample. I do not consider this prejudicial, 
as it would require less fire to burn the brick, though on the other hand 
the contraction would be greater and the brick more porous. I may say 
_ respecting the Miranda clay that I am indebted to Mr. Tunny for this 
analysis, but that a sample analysed some time since for the Wharekawa 
Coal Co. contained 11 per cent. of bituminous matter, which was distri- 
buted finely throughout, as if permeated by it. The Waikato and Bay of 
Islands clays have been most used in Auckland for manufacturing purposes, 
the former being largely used by the gas works, foundaries, and glass works 
of this city, and I believe the furnaces for the smelting of iron sand at 
- Taranaki and the Manakau Heads have been made of the same material. 
With reference to its use for melting-pots at the glass works, the manager 
complained bitterly of the manner in which it had been collected at the 
mines and mixed with worthless material, by which it was greatly deterio- 
rated, and it was found necessary in consequence to mix some imported 
Sydney clay with it. One peculiarity of the Waikato clay is its extreme 
friability after exposure, which is taken advantage of by the manufacturers 
before alluded to, and though at first a large sum was paid for the grinding 
of it, now it is simply left to the action of the weather for a few weeks, and 
is then in a state of fine division. The great drawback to the increased 
use of fire-bricks is the distance of the known deposits from the centre of 
