554 NEW YORK STATE MUSEUM 



Cone no. 1 melts at the same temperature as an. alloy co^mposed 

 of one part of platinum and nine parts of gold, or at 1100° C. 

 Cone no. 20 melts at the highest temperature obtained in a porce- 

 lain furnace, or at 1530° C. The difference between any two suc- 

 cessive numbers is 20° C. The upper member of a series is cone 36, 

 which is composed of a very refractory clay slate, while cone 35 is 

 composed of Zettlitz kaolin. 



A lower series of numbers was produced by Cramer, who mixed 

 with boracic acid the materials already mentioned. Hecht obtained 

 still more fusible ones by adding both boracic acid and lead to the 

 cones. The result is that we have now a series of 58 numbers, the 

 fusion of the lowest being 710° C, and that of the highest 

 1850° C. 



As the cone reaches its fusion point, it begins to bend over, and it 

 is considered that the kiln has reached the fusion temperature when 

 the tip bends over so as to touch the base. 



For practical purposes these cones are very successful, though 

 their use has been perhaps somewhat unreasonably discouraged by 

 some. The full series can be obtained from Messrs Seger and 

 Cramer, of Berlin, for 1 cent each (or about 2^ cents each, includ- 

 ing duty and expressage), or nos. .010-10 can be obtained for 1 

 cent each from Prof. E. Orton jr, of Columbus university, 

 Columbus, O. Recently this series of cones has been restandard- 

 ized by Seger and Cramer, The new table is given herewith. 



