2203. Roman Cement

2203.    Roman Cement. Calcine 3 parts of any ordinary clay, and mix it with 2 parts lime; grind it to powder, and calcine again. This makes a beautiful cement, improperly called Roman, since the preparation was entirely unknown to the Romans.

2204. New Plastic Material

2204.    New Plastic Material. A beautiful plastic substance can be prepared by mixing collodion with phosphate of lime. The phosphate should be pure, or the color of the compound will be unsatisfactory. On setting, the mass is found to be hard and susceptible of a very fine polish. The material can be used extensively, applied in modes that will suggest themselves to any intelligent artist, to high class decoration.

2205. Concrete

2205. Concrete. A compact mass, composed of pebbles, lime, and sand, employed in the foundations of buildings. The best proportions are 60 parts of coarse pebbles, 25 of rough sand, and 15 of lime; others recommend 80 parts pebbles, 40 parts river sand, and only 10 parts lime. The pebbles should not exceed about 1/2 pound each in weight. Abb'e Moigno, in his valuable scientific journal, " Les Mondes," relates his personal experience with a concrete formed of fine wrought and cast iron filings and Portland cement. The Abbe states that a cement made thus is hard enough to resist any attempts to fracture it. As he states that the iron filings are to replace the sand usually put into the mixture, we presume that the relative quantities are to be similar.

2206. Concrete Floors and "Walks

2206. Concrete Floors and "Walks. Compost for bam and kitchen floors: - After the ground on which the floor is intended to be made is leveled, let it be covered to the thickness of 3 or 4 inches with stones, broken small, and well rammed down; upon which let there be run, about 11/2 inches above the stones, 1 part by measure calcined ferruginous marl, and 2 parts coarse sand and fine gravel, mixed to a thin consistence with water. Before this coating has become thoroughly set, lay upon it a coat of calcined marl, mixed with an equal part of line sand, 1 to l1/2 inches thick, leveled to an even surface. The addition of blood will render this compost harder. The calcined marl mentioned above is the

Portland cement of commerce. (See No. 2195.)

2207. Concrete Gravel Walk

2207.     Concrete Gravel Walk. Dig away the earth to the depth of about 5 inches, then lay a bottom of pebbles, ramming them well down with a paving rammer. Sweep them off as clean as possible with a broom, and cover the surface thinly with hot coal tar. Now put on a coat of smaller gravel (the first bed of pebbles should be as large as goose eggs), previously dipped in hot coal tar, drained, and rolled in coal ashes, with an intermixture of fine gravel, and roll it down as thoroughly as possible. Let the roller run slowly, and let a boy follow it with a hoe to scrape off all adhering gravel. Next put on a coat of fine gravel or sand, and coal tar, with some coal ashes, to complete the surface, and roll again as thoroughly as possible; the more rolling the better. It will take some weeks to harden, but makes a splendid hard surface which sheds water like a roof. Do not use too much tar. It is only necessary to use enough to make the ingredients cohere under pressure, and a little is better than too much. Such a surface will last in a farmyard a great while.