512 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



dissolve in it sufficient Cologne or Flanders glue to form a 

 thick, sirupy liquid. Neither glycerine nor sirup should be 

 added, and it should be kept in well-closed bottles. 18 (7, 

 February^ 1876, 95. 



GELATIN AND BICHROMATE OF POTASH CEMENT FOR GLASS. 



Dr. Schwarz has employed with success, for cementing 

 broken glass-ware, a five to ten per cent, solution of gelatin, 

 to which one part of bichromate of potash for each five parts 

 of gelatin had been added, in solution. Both surfaces of 

 fracture were coated, as uniformly as possible, with the freshly 

 made solution, and held in position with a cord, and exposed 

 to sunlight for several hours, after which the cement was 

 not affected by hot water, and the fracture could scarcely 

 be detected. 14(7, CCXVIII., 61. 



COPPER ALLOY THAT WILL ADHERE TO GLASS. 



The following alloy, it is said, will attach itself firmly to 

 glass, porcelain, or metal : Twenty to thirty parts of finely 

 pulverulent copper (prepared by precipitation or reduction 

 with the battery) are made into a paste with oil of vitriol. 

 To this seventy parts of mercury are added, and well tritu- 

 rated. The acid is then washed out with boiling water, and 

 the compound allowed to cool. In ten or twelve hours it 

 becomes sufficiently hard to receive a brilliant polish, and to 

 scratch the surface of tin or gold. When heated it is plastic, 

 but does not contract on cooling. Zrow, V.,683. 



A NEW GLASS. 



Following closely upon the public announceme'nt of the 

 results obtained by MM. De la Bastie and Peiper in the art 

 of toughening glass comes the statement that Mr. Mackin- 

 tosh, of Westminster, England, a civil engineer, who is rep- 

 resented to have devoted much time to the processes of tem- 

 pering metals and alloys, has invented a method of hardening 

 glass. From what has been published, it appears that Mr. 

 Mackintosh, in his process, has started from his theory that 

 the lower the temperature of the liquid bath in which cer- 

 tain heated bodies are plunged, the harder such bodies be- 

 come. Mr. Mackintosh affirms, as the result of his observa- 

 tions, that glass, graphite, uncrystallized carbon, slag, and 



