292 New Building Material. 



lime to fill the spaces in the sand and gravel will prevent 

 cohesion. 



The lime should be thoroughly slacked before mixing with the 

 sand, or pieces of lime will slacken in the wall, and by expansion 

 will injure the wall, and prove a waste of lime. 



But the last, and " not least," important matter in making good 

 concrete is to have the materials thoroughly mixed before placing 

 them in the moulds. This is rarely, if ever, well performed in 

 mixing mortar either for concrete or brick walls, or for plaster- 

 ing. It is hard work to mix mortar by hand ; and sufficient time 

 is not devoted to mix it properly. 



To remedy this difficulty, I have invented a machine for mixing 

 mortar by horse-power, with a view of obtaining a patent. This 

 machine can be constructed at an expense of $10 to $20, accord- 

 ing to size ; and by the aid of one or two horses and a stout boy, 

 it will mix as much mortar in a day as six to ten men, and mix- 

 ing the mortar at least ten times as much as it is ever mixed by 

 hand, thus saving labor and lime (the more it is mixed the less 

 lime is required), and making a much stronger concrete or valua- 

 ble mortar for other uses. 



Besides, this machine may be used to draw the sand from the 

 sand-bed, or deposite, to the building, mixing the mortar perfectly 

 in its transit ; and requiring but a small amount of extra power 

 in thus transporting it. 



Now for the comparative expense of building with concrete 

 and sand brick, and the real permanency, value, and beauty of 

 the two when completed : — 



In the sand brick, cohesion takes place as the result of 

 great pressure : while in concrete, cohesion takes place naturally 

 by the use of liquid lime, properly mixed with the gravel 

 and sand. 



In the case of sand brick, the sand and lime are mixed 

 by hand, placed in a mould, subjected to a great pressure in 

 an expensive machine, removed and left to harden in a position 

 to secure it from injury by storms, &c., and then laid into the 

 wall with no small expense and skill in order to make even 

 a building of tolerable strength and beauty ; while the mortar of 

 the concrete is mixed by horse-power, and shoveled at once into 

 the moulds, in wliich it performs its own pressing and drying, and 



