M. TECHNOLOGY. 569 



LEATHER GLUE. -^ 



A substance known as " leather glue " is prepared by mix- 

 ing ten parts of sulphide of carbon with one of oil of turpen- 

 tine, and adding enough gutta-percha to thicken the mass. 

 The leather surfaces to be united must be freed from oil, 

 which is accomplished by subjecting them to pressure by lay- 

 ing the leather upon blotting-paper and applying a hot iron. 

 After tacking together the edges to be joined with the ce- 

 ment, they are to be kept under pressure until the glue is 

 entirely dry. 15 (7, 1872, xxn., 352. 



IMPROVED ELASTIC BANDS. 



The ordinary elastic bands, Avith rubber threads woven 

 into them, lose their elasticity in a short time by action of 

 the atmosphere ; but bands free from this defect, and at the 

 same time more elegant and stronger, are made at no greater 

 cost by causing two strips of cloth, previously coated on the 

 inner surfaces with a solution of India rubber in benzine, 

 and with a band of stretched gum threads or a gum band 

 inserted between them, to pass through rollers, compacting 

 the three by this pressure into a firm fabric. 25 C, XLV., 

 362. 



THE SPONGE TRADE. 



According to the "Report on Commercial Relations for 

 1871," sponge is exported from Nassau to the United States, 

 England, and France. Within the last two years the greater 

 l^ortion has come to the United States. 



About 500 vessels are engaged in " sponging," and 4000 

 men find employment. The several qualities are shipped un- 

 der the names of sheep-wool, glove, fine reef, velvet, yellow, 

 and grass sponge. The grounds from wdiich the sponge is 

 taken are east, w^est, and south of ISTassau ; the finest being 

 taken from William's Cay, Andros Island. These last are 

 used for surgical purposes, and are exported to the United 

 States, as Europe is supplied from the Mediterranean. 



The sponge obtained at Abaco is exported to France ; the 

 same quality being found at Key West, the American mar- 

 ket is supplied from the latter place. Commercial Melations^ 

 1871. 



