An ordinary damp-proof building course may be made by mixing 12 gal. coal-tar, 1/2 cwt. pitch, and 2 gal. creosote oil. It will take nearly an hour to melt this quantity, and it should not boil more than a few minutes. After being poured upon the wall, which should be first swept and quite dry,it should be sprinkled with sand. The above quantities will cover about 12 sq. yd.