Building Materials. 



31 



They absorb water very rapidly : one specimen gaining 11*523 

 per cent, by weight in 20 hours, and another 13*257 per cent. 

 When it had absorbed its maximum quantity it was easily 

 crumbled between the fingers. A good Brick does not absorb- 

 so much water as the Melbourne Sandstones. One of 

 Ramsay^s manufacture was immersed for 20 hours and its 

 increment was 2*841 per cent, and after 72 hours 3*216 per 

 cent. Subjected to the ordinary tests the common red Brick 

 very rapidly disintegrates. It may be inferred that a small 

 amount of force would be required to crush it ; and it is a 

 matter of regret that I have no present means of ascertaining 

 the exact weight. Such a material is certainly not suited 

 for buildings three storeys high ; and yet a considerable 

 number of houses in this City are so constructed. 



There is a very slight difference in the quality of the 

 Melbourne Bricks. The fault is owing not so much to the 

 material of which they are composed, as to theimproper manner 

 in which they are manufactured. They are usually burnt in 

 clamps, and the clay is not ground and tempered as is 

 customary in other countries. If suitable kilns were erected, 

 and care was taken in the preparation of the raw material, it 

 would be possible to make as good Bricks in Melbourne as 

 any that are imported, excepting perhaps the fire bricks. 



Bricks which are made of pure clay, and heated to vitri- 

 fication, have been found to resist atmospheric influences 

 most completely. Such a material is unsuitable for high 

 walls, as its cohesive strength is not so great as when a pro- 

 portion of sand is used. The best English bricks are manu- 

 factured from a clay which contains about one-fourth of sand, 

 and if it should contract considerably in burning, the pro- 

 portion of the latter is increased. Much of the fine clay 

 around Melbourne contains lime and magnesia, but not in 

 excess; and if it were mixed with the superficial clay at 

 present in use, a manifest improvement would be apparent in 

 the bricks. All materials of this manufacture are rendered 

 more durable by glazing. This is effected by throwing a due 

 proportion of salt into the furnace, the result of which is the 

 vitrification of the outer crust. When the manufacture is 

 otherwise imperfect, this system, if properly conducted, will 

 lessen the tendency to decay, and obviate the imsightly and 

 expensive system of painting, which is often resorted to in 

 Melbourne. Not until we have the same spirit that animates 

 the manufacturers in England and America will this branch 

 of industry be fully developed. Machinery has there super- 



