768 



Popular Science Monthly 



when it is to be used in sanding machines, 

 there is an additional backing of cloth. 

 Garnet-paper is not so sharp as sandpaper, 

 but it has the advantage that the edges and 

 corners of the particles do not wear smooth, 

 but break off at sharp angles. Hence it 

 cuts satisfactorily just so long as it adheres 

 to the paper. 



Emery 



Emery is a variety of 

 corundum, and is sec- 

 ond only to the dia- 

 mond in hardness. 

 When used for the 

 abrasion of metals, it 

 may be spread on the 

 surface of paper, cloth, 

 or wood. In this shape 

 it is used mostly for 

 smoothing and polish- 

 ing metal. Emery may 

 also be mixed with a 

 kind of earthenware, 

 and then baked, to 

 make "emery stone." 

 Emery wheels are thus 

 made, and they are so 

 hard and strong that they can be revolved 

 at a high velocity, to cut very effectively. 

 Emery in its powdered form is used to 

 grind valves to their seats and to make 

 them airtight. 



Whetstones are quarried and 

 cut from natural rocks, found 

 mostly in Arkansas. The 

 best ones are found near 

 Hot Springs, Ark. The 

 coarser ones, such as are 

 used for whetting 

 scythes, etc., are called 

 Washita stones, while 

 the fine white ones are 

 called Arkansas stones. 



Other natural abra- 

 sives used in the arts are 

 tripoli, made from a sili- 

 cious sandstone, and used 

 for polishing horn, shell 

 and metal; rotten stone, 

 an infusorial earth, used 

 in rubbing down varnish ; 

 pumice, made from a 

 volcanic ash, also used in 

 rubbing down varnish 





Whetstones are quarried and cut from 

 natural rocks found mostly in Arkansas 



Emery is second only to the diamond 

 in hardness. It is the strongest abrasive 



and rouge, made 

 from sulphate of iron, and used for polishing 

 glass. It will be observed that all of the 

 abrasives mentioned are mineral products 

 except the steel wool. 



Half-Soling Rubber Overshoes 

 to Give Longer Wear 



AS rubber overshoes are still in high favor 

 l as a necessary evil for keeping the feet 

 dry in muddy or wet weather, any idea that 

 promises to make the rubber give longer 



service should appeal to 



economical people. 



A friend of the writer 

 gets more than double 

 wear out of his rubber 

 overshoes by half-soling 

 them with rubber. He 

 owns an automobile, and 

 when the soles of his 

 overshoes become thin, 

 but are still watertight, 

 he takes a torn and other- 

 wise useless inner tube 

 and cuts a half-sole from 

 it. This half-sole is then 

 cemented to the rubber 

 shoe — after both sole and 

 shoe have been cleaned 

 thoroughly and roughened 

 with sandpaper — u sing 

 ordinary rubber cement 

 and clamping or holding both tightly together 

 so that a secure union is obtained. The 

 same kind of cement is used as for repairing 

 bicycle tires, and if used according to the 

 directions that accompany it, a 

 satisfactory job will result. 

 An attached sole of 

 this kind will^often give 

 longer wear than the 

 original. If the heels 

 also are worn, they can 

 be repaired in the same 

 manner. If you can- 

 not procure an old 

 rubber inner tube, 

 most any kind of pli- 

 able sheet rubber will 

 do, providing it is of 

 the proper thickness. 

 Halfsoles for arctics have 

 been made from a piece 

 of large-size rubber hose, 

 split and straightened, 

 and have given excellent 

 service. The rubber used 

 for this purpose must not 

 be hardened from age. 



If it is not possible to procure an old piece 

 of rubber, an extra half-sole or heel can be 

 purchased from a rubber dealer. These 

 come in different sizes and shapes. 



