294 SEALE. 



The exact technique * of welding tortoise-shell is as follows : 



When two pieces of shell are to be joined, the two edges are beveled so that 

 one inclined edge may lie upon the other. The edges are scraped perfectly clean, 

 contact with the fingers or any greasy substance being carefully guarded against. 

 A piece of paper is then bound around the overlapping edges and fastened 

 with a string. A pair of flat tongs or pincers, something like hair-dresser's tongs, 

 are then heated and applied to the sliell, one ja\\- of the pincer-s above and the 

 other beneath, by means of which the shell is grasped throughout the length of 

 the seam or overlap. By holding it a short time in this position, the heat of 

 the iron penetrates through the paper, softens the shell, and causes the two 

 pieces to unite firmly. Sometimes two pieces of shell are united by means of 

 boiling water as follows: The two edges are overlapped, two pieces of metal are 

 placed along the joining, the shell is placed in a press, and the whole is immersed 

 in boiling water. As the shell softens, the press is screwed more tightly, by 

 which the two pieces of shell become firmly united. Owing to the fact that the 

 shell becomes mobile with heat, it is easily molded into almost any desired shape 

 by means of boiling water and the screw press, and even small bits of shell 

 are utilized by being thus welded together. If too much heat is used the shell 

 becomes blackened, consequently in many places, especially in Japan, most of the 

 work is accomplished b)' hand graving, following a pattern as in scroll work. 

 The same method is followed in Manila, where the outfit of the workman 

 consists simply of scraper, saws, files, and a bench. Manila has two small 

 factories employing about six men (all Chinese), where crude combs (Plate VI, 

 figs. I to 6) of tortoise-shell are made. Tliere is also a small factory in Iloilo. 

 All the work in this place is done by hand and is of the crudest sort. 



The method used to weld tortoise-shell in Japan differs in slight detail. 

 - Dr. Shigeho Tawaka of the Zoological Institute, College of Science, Im- 

 perial University of Tokyo, kindly supplies the following information. 



First of all, shells which are to be welded are just dipped in water and thus 

 moistened, the shells are then put in between two thin pieces of magnolia 

 wood {Magnolia liypoleuca) and then the whole thing is moderately pressed with 

 a pair of heated pincers which have been dipped in water an instant before 

 operating (a hissing sound is the usual sign of these being suSiciently heated). 

 The welding of the shell is thus completed. The reason why they use the magnolia 

 pieces is to avoid the direct contact between the heated pincers and the shell. 

 The temperature of the pincers is not scientifically made known, being said to 

 be the trade secret kept among the preparators. 



The appearance of tortoise-shell frequently is given to horn by In'ushing 

 it over with a paste made of two parts lime to one part litharge, and a 

 little soda lye, which is allowed to dry on. Artificial tortoise-shell is 

 manufactured by melting gelatine and various metallic salts. 



VALUES AND GRADES OF PHILIPPINE TORTOISE-SHELL. 



It is very difficult to arrive at a true valuation of tortoise-shell, owing to its 

 variations and the reluctance of the Chinese merchants, who now control the 

 trade, to give out any facts regarding the matter, but 4 different gxades are 



» Sim'inonds. Commercial Products of the Sea. New York (1895), 355. 



