EMERY 267 



The finest omory that is obtained from the manufacturers is that which floats in the 

 atmosphere of the stamping-room, and is deposited on the beams and shelves, from 

 which it is occasionally collected. The manufacturers rarely or never wash the emery; 

 this is mostly done by the glass-workers, and such others as require a greater degree 

 of precision than can be obtained by sifting. 



The following table shows the number of wires usually contained in the sieves, and 

 the names of the kinds respectively produced by them : 



Wires. 



Corn emery , . 16 



Coarse grinding emery . . . . .; t : * 24 



Grinding emery . . . . . . > 36 



Fine grinding emery . . , . * - . 46 

 Superfine grinding emery . . . v >-.-' 53 

 Coarse flour emery . . . '.-.'*; < * -.- - .:- 60 



Flour emery . . . . . * ' * -.. : 70 



Fine flour emery . . . *"; * . -* 80 

 Superfine flour emery . . . -* t -.'.. ..'. 90 



Washing emery by hand is far too tedious for those who require very large quanti- 

 ties of emery, such as the manufacturers of plate glass and some others, who generally 

 adopt the following method : Twelve or more cylinders of sheet copper, of the common 

 height of about two feet, and varying from about three, five, eight, to thirty or forty 

 inches in diameter, are placed exactly level, and communicating at their upper edges, 

 each with the next, by small troughs or channels ; the largest vessel has also a waste- 

 pipe near the top. At the commencement of the process, the cylinders are all filled 

 to the brim with clean water ; the pulverised emery is then churned up with abundance 

 of water in another vessel, and allowed to run into the smallest or the three-inch 

 cylinder, through a tube opposite the gutter leading to the second cylinder. The water 

 during its short passage across the three-inch cylinder, deposits in that vessel such of 

 the coarsest emery as will not bear suspension for that limited time ; the particles 

 next finer are deposited in the five-inch cylinder, during the somewhat longer time the 

 mixed stream takes in passing the brim of that vessel ; and so on. Eventually the 

 water forms a very languid eddy in the largest cylinder, and deposits therein the very 

 fine particles that have remained in suspension until this period ; and the water, 

 lastly, escapes by the waste-pipe nearly or entirely free from emery. In this simple 

 arrangement, time is also the measure of the particles respectively deposited in the 

 manufacture to which the emery is applied. When the vessels are to a certain degree 

 filled with emery, the process is stopped, the vessels are emptied, the emery is care- 

 fully dried and laid by, and the process is recommenced. 



Holtzapffel informs us that he has been in the habit, for many years, of employing 

 emery of twelve degrees of fineness, prepared by himself by washing over. 



For optical purposes, Mr. Eoss mixes four pounds of the flour of emery of commerce, 

 with one ounce of powdered gum-arabic, and then throws the powder into two gallons 

 of clear water ; and he collects the deposit at the end of 10" and 30", and 2', 10', 20', 

 and 60', and that which is not deposited by one hour's subsidence is thrown away as 

 useless for grinding lenses. 



Emery paper is prepared by brushing the paper over with thin glue, and dusting 

 the emery-powder over it from a sieve. There are about six degrees of coarseness. 

 Sieves with thirty and ninety meshes per linear inch are in general the coarsest and 

 finest sizes employed. When used by artisans, the emery-paper is commonly wrapped 

 round a file or a slip of wood, and applied just like a file, with or without oil, accord- 

 ing to circumstances. The emery-paper cuts more smoothly with oil, but leaves the 

 work dull. 



Emery-cloth only differs from emery-paper in the use of thin cotton cloth, instead 

 of paper, as the material upon which the emery is fixed by means of glue. The emery- 

 cloth, when folded around a file, does not ply so readily to it as emery-paper, and is 

 apt to unroll. Hence smiths, engineers, and others, prefer emery-paper and emery- 

 sticks ; but for household and other purposes, where the hand alone is used, the 

 greater durability of the cloth is advantageous. 



Emery-sticks are rods of board about eight or twelve inches long, planed up square ; 

 or with one side rounded like a half-round file. Nails are driven into each end of the 

 stick as temporary handles ; they are then brushed over, one at a time, with thin 

 glue, and dabbed at all parts in a heap of emery-powder, and knocked on one end to 

 shake off the excess. Two coats of glue and emery are generally used. The emery- 

 sticks are much more economical than emery-paper wrapped on a file, which is liable 

 to be torn. 



Emery-cake consists of emery mixed with a little bees'-wax, so as to constitute a 



