540 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



slightly warm with red ochre mixed with a little yellow, 

 and when perfectly dry coat a second time. Then rub the 

 whole carefully with moistened shave-grass, and apply, witli 

 a bristle-brush, the bronze, of copper and brass or tin, mixed 

 with alcohol. The article, as well as the bronze, must be 

 kept warm during the operation, either in the sun or near 

 a fire. Two or three coats are necessary to produce a per- 

 fect effect. 5 (7, 20, 158. 



CASTING CYLINDERS, CALENDERS, TUBES, PISTONS, ETC., OF 



GLASS. 



According to a process patented by Chedgey, glazing- 

 rollers, calenders, etc., may be cast of glass, in a cylindrical 

 mould, provided with a movable bottom to which a rod is 

 attached, which forms the core of the roller, by placing the 

 movable bottom near the top of the mould at first, and grad- 

 ually lowering it as the glass is poured in, thus preserving 

 the casting free from air-bubbles. The casting is then an- 

 nealed in the mould, and after the axis has been properly 

 centred by wooden wedges, and fastened with cement, it is 

 turned in a lathe with a diamond, the aid of emery, or sand 

 and water, and polished as usual with rouge or putty. Pump 

 pistons may be cast in the same way, and the rods fastened 

 as usual by screw and nut. Cylinders to be turned and pol- 

 ished internally on the lathe are preserved from fracture by 

 cementing them into a metallic cylinder, formed in seg- 

 ments, with plaster, and employing emery and water, and a 

 polishing cylinder covered with felt. Straight and bent 

 tubes can also be cast, with the advantage that they may be 

 of any desired thickness. 14 C, CCXIL, 254. 



PREPARATION OF CORALLINE. 



From a recent study of coralline, Commaille concludes: 1. 

 That it is obtained at temperatures from 239 to 302, the 

 product being larger and the process more rapid at the low- 

 er temperature. 2. The quantity of oxalic acid required is 

 not as large as generally stated. 3. Coralline forms no def- 

 inite salts, but only lakes. 4. Yellow coralline is no acid, 

 and rosolic acid is consequently a misnomer. 5. Red coral- 

 line is no amide of the yellow, since it contains no nitrogen. 

 32 C, May 16, 1 874, 238. 



