CLAYS AND CLAY INDUSTRY. 



Composition. r— Fusing point— > 



°F. ^ °C. 



4.9 ALO349S1O2 2,858 1,570 



5.4 Alo0 3 S4Si0 2 2,894 i,590 



6.0 ALO360S1O2 2,930 1,610 



6.6 Al 2 0s66Si0 2 2,966 1,630 



7.2 ALOs72Si02 3,002 1,650 



20 Al20 3 20oSi0 2 3,038 1,670 



Si02 3,074 1,690 



Si02 3,no 1,710 



S1O2 3.146 1,730 



Si0 2 3,182 1,750 



Si02 3.218 1,770 



Si0 2 3-254 1-790 



Si02 3,290 1,810 



Si02 3,326 1,830 



S1O2 3-362 1,850 



If the heat is raised too rapidly the cones which contain much 

 iron swell and blister and do not bend over, so that the best 

 results are obtained by the slow softening of the cone under a 

 gradually rising temperature. 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 of different numbers in the kiln, so that warning can be 

 had, not only of the end point of firing, but also of the rapidity 

 with which the temperature is rising. 



In determining the proper cone to use in burning any kind of 

 ware, several cones are put in the kiln, as for example, numbers 

 .08, 1 and 5. If .08 and 1 are bent over in burning and 5 is 

 not affected, the temperature of the kiln is between 1 and 5. 

 The next time numbers 2, 3 and 4 are put in, and 2 and 3 may 

 be fused, but 4 remains unaffected, indicating that the temperature 

 reached the fusing - point of 3. 



No. c 



f 





cone 







22 



{0.3 

 I0.7 



K2O} 

 CaO j 



23 



[0.3 

 (0.7 



K2O) 

 Cap) 



24 



{0.3 



(0.7 



K2OI 

 CaO) 



25 



1 0.3 

 {0.7 



K2O) 

 CaO) 



26 



[0.3 



(0.7 



K 2 0{ 

 CaO) 



27 



[0.3 



(0.7 



K2O I 

 CaO) 



28 



AI2O3 10 



29 



AI2O3 8 



30 



AI2O3 6 



31 



AI2O3 5 



32 



AI2O3 4 



33 



AI2O3 3 



34 



AI2O3 2.5 



35 



AI2O3 2 



36 



AI2O3 1.5 



