WORKING OF IVORY 251 



they are put in water to soak, at various temperatures and 

 for various lengths of time, this depending upon the special 

 condition of the tusk that has been cut up. The soaking 

 process having been completed, the parts of the keys are 

 very carefully and slowly dried out, so as to guard them 

 from warping, "checking," or cracking. To whiten them 

 they are then put for a time in a bath of peroxide of hydro- 

 gen, in earthen crocks 18 in. high and 14 in. across, the 

 strength of the solution and the duration of the immersion 

 (from 24 to 48 hours) depending upon the special conditions 

 of the ivory to be treated. The keys are then taken out, 

 dried, and placed on racks that are two rows wide and 3 

 ft. long. These racks have rows of tin slats to hold the 

 keys in place, and are set at an angle against the glass 

 panes of a building which resembles a greenhouse in char- 

 acter. The sunlight penetrating the glass bleaches the 

 ivory in from one day to a week's time. The keys when 

 they are dried and bleached are carefully sorted for the 

 various qualities. They are again sorted according to colour 

 and grain. Some are compact and slightly grained, others 

 are coarse grained. The sorting is most expertly done by ex- 

 perienced young girls who sort them into lots of fifty-two. 

 They are then ready to be placed on the piano board. 

 The board is cut out of a piece of pine or bass wood exactly 

 the size of the keyboard. A machine then cuts the grooves 

 that will be ultimately removed, in which the thirty-six flats 

 are placed. The board is now covered with glue and whit- 

 ing and pressed with an aluminum plate to which glue does 

 not adhere; the glue while hot would adhere to other metals, 

 but does not to aluminum because it is so good a conductor 

 of heat. When the excess of glue has been scraped off by 

 a small steel tool, the board is placed on a flat machine and 

 the 104 keys are laid on, fitting perfectly, and then a pres- 

 sure secures them in place and the entire surface is polished. 



