BUILDING AND ORNAMENTAL STONES. 317 



ther reduced by means of wet sand and emery of varying degrees of 

 fineness. Small blocks are now usually ground on a revolving iron 

 bed, on which the abrading material is shoveled and kept wet by a 

 stream of water from overhead. With larger blocks a heavy slab of 

 stone is drawn by the workmen back and forth across the surface on 

 which the wet sand has already been placed. On the finer grades of 

 white marble emery is not used, as it stains ; fortunately, owing to the 

 softness of these stones, it is readily dispensed with. After being 

 ground, the surface is rubbed by a sharp, evenly gritted sandstone 

 called a " hone," and then with pumice-stone. 



On granites it is often customary to give a " skin coat" by rubbing the 

 block, after the final emerying on the smooth, wet grinding bed, without 

 any abrading material, until a perfectly smooth surface and dull polish 

 is obtained. When this point is reached — and the surface must be 

 quite free from scratches and blemishes, or a good polish is impossi- 

 ble — the polish is produced by means of polishing putty (oxide of tin) 

 rubbed on with wet felt. In cheap work it is customary to use oxalic 

 acid in connection with or entirely in place of the polishing putty. This 

 enables the production of a polish with less labor, but it is also less 

 durable. 



A high grade of polish can only be produced by skilled workmen, and 

 each one has his own peculiar methods, varying in trifling particulars 

 from that given above. In mauy of the larger works where steam 

 power is used, it is said to be customary to mix a quantity of very 

 finely ground metallic lead with the putty. By this means a higher 

 gloss is produced, and also one that is very durable. All the larger 

 works now use machinery in both grinding and polishing. Descriptions 

 of these will be given in the following chapter. 



Sundry attempts have been made to utilize the sand-blast process, so 

 extensively used in glasswork, for carving on stone; but so far, with 

 few exceptions, these attempts have met with but poor success. In 

 1875-'7G, Messrs. Sheldon & Slason, of West Eutland, having a large 

 Government contract in preparing head stones for soldiers' graves in 

 national cemeteries, introduced the system with considerable success. 

 The process consisted in covering those parts of the stone to be left un- 

 cut with an iron shield, while letters and figures of chilled iron were 

 placed upon those portions which were to stand out in relief. The blast 

 then being directed against the stone cut away very quickly the unpro- 

 tected parts. By this means the name, compauy, regiment, and rank of 

 soldiers, could be cut on a stone in less than five minutes, and two hun- 

 dred and fifty-four thousand stones thus lettered and having dimensions 

 of 3 feet in length, 10 inches in width, and 4 inches in thickness, were 

 placed in the national cemeteries at a cost of but $864,000. The sand- 

 blast process has also been used with good results on the hard red 

 quartzite of Sioux Falls, as will be noted later. 



