CLAYS OF NEW YOK: 



^ 



557 



Composition and fusing points of Seger cones (continued) 



No. of cone 





Composition 





Fusing point 











"F 



"C 



23 



(0.3 K2O) . 

 |0.7 CaO r 



.4 AI3O3 54 



Si02 



2 894 



1 690 



24 



j 0.3 K2O ] n 



|0.7 CaOp 



AI2O3 60 



Si02 



2 930 



1 610 



25 



j . 3 K2O ( n 



1 0.7 CaO I ^ 



6 AI2O3 ee 



SiOs 



2 966 



1 630 



26 



jO.3 K20i „ 

 |0.7 CaO f ' 



2 AI2O3 72 



SiOs 



3 002 



1 650 



. 27 



io:?Ca8h^ ^1^200 



SiOa 



3 038 



1 670 



28 





AlgOg 10 



AI2O3 8 

 AI2O3 6 

 AI2O3 5 

 AI2O3 4 

 AI2O3 3 

 AI2O3 2.5 

 AI2O3 2 

 AI2O3 1.5 



SiOa 

 SiOa 

 SiOa 



SiOg 



Si02 



Si02 

 Si02 



Si02 



SiOa 



3 074 

 3 110 

 3 146 

 3 182 

 3 218 

 3 254 

 3 290 

 3 326 

 3 362 



1 690 



29 

 30 





1 710 

 1 730 



31 





1 750 



32 

 33 

 34 

 35 

 36 







1 770 

 1 790 

 1 810 

 1 830 

 1 850 









The theory of these pyramids is that the cone bends over as the 

 temperature approaches its fusing point. If the heat is raised too 

 rapidly the cones which contain much iron swell and blister and do 

 not bend Qiver, so the best results are obtained by the slow softening 

 of the cone under a gradually rising temperature. For practical 

 purposes these cones are considered sufficiently accurate. 



In actual use they are placed in the kiln at a point where they 

 can be watched through a peep hole but at the same time will not 

 receive the direct touch of the flame from the fuel. It is always 

 well to put two or more cones in the Mln, so that warning can be 

 had not only of the approach of the desired temperature, but also of 

 the rapidity with which the temperature is rising. 



In order to determine the temperature of a kiln several cones of 

 separated numbers are put in, as for example: .07, 1, and 5. Sup- 

 pose .07 and 1 are bent over in burning but 5 is not affected, the 

 temperature of the kiln is between 1 and 5. The next time nos. 2, 3 



