CHAPTER XX. 



BUILDING MATERIALS. 



To those who are intrusted with the erection of buildings, a knowledge 

 of the different materials used in their construction is of very great 

 importance, so that they may be able to make a judicious selection of 

 them. On many estates the local circumstances are such that there 

 is not. much choice in this respect ; but, under any circumstances, an 

 acquaintance with the different materials at the builder's disposal will 

 enable him to judge which will be the most economical for his purpose, 

 and also at the same time the most permanent. Amongst the many 

 different materials used for building purposes, I propose making a few 

 remarks on the following : 



1. Granite. 8. Cements. 



2. Sandstones. 9. Concretes. 



3. Limestones. 10. Timber. 



4. Bricks. 11. Metals. 



5. Slates. 12. Glass. 



6. Tiles. 13. Paints. 



7. Mortar. 



1. Granite. Granite is composed of different substances, such as 

 quartz, felspar, and mica. These are easily distinguished on an exa- 

 mination of a piece of granite. The quartz has a transparent appear- 

 ance, very much like glass, with a dim hue ; the felspar is sometimes 

 found of a white colour and sometimes red, commonly of an opaque 

 appearance, and is composed of aluminous and silicious matter, with a 

 small mixture of potash and lime ; mica is of a glittering appearance, 

 and very much resembles the scales of a fish when removed in pieces. 

 In some granites a substance called hornblende is found in place of 

 mica. It is of a dark colour, consisting of alumina, magnesia, flint, and 

 a proportion of the oxide of iron. 



Granite rocks are found over a very great portion of Europe in 

 Scotland, England, and Ireland, Germany and Switzerland. The chief 



