420 K T. Allen, F. K Wright and J. K. Clement— 



The curves in this figure (fig. 13) were obtained by heating 

 large charges (about 100 grams) of orthoclase to a temperature 

 which caused a complete change of state. During the time 

 of melting, which, in the alkaline feldspars, extends over 

 quite an interval, the rate at which the temperature rises is 

 retarded by heat absorption, but the change is so slow that 

 this retardation is very slight. The indentation in the curve is 



Table VIII (see tig. 11). 



Table IX (see fig. 12). 







Wollas- 



Pseudo- 



















tonite 



Wollas- 











Albite 







Time. 



glass. 



tonite. 



Wollastonite. 



Time. 



glass. 



Albite. 







rain. 



15000 



15000 



15000 



15000 



15000 







min. 



15000 



15000 







1 L40o 



11300 



10600 



9900 



11100 







11100 



11850 



1 



u 



11450 



10905 



9960 



9170 



10380 



1 



a 



9900 



315 







12210 



11450 



10520 



9700 



875 





\ 



9900 



720 



2 



t< 



12890 



12115 



11350 



10585 



11560 



2 



a 



10525 



12250 







13445 



734 



12175 



11495 



12215 







11430 



800 



3 



a 



790 



13208 



790 



12245 



715 



3 



u 



12365 



13140 







14065 



595 



13305 



.12840 



13160 







13145 



478 



4 



a 



262 



880 



680 



13215 



484 



4 



a 



695 



716 







418 



14114 



970 



550 



760 







14075 



919 



5 



u 



529 



281 



14185 



818 



974 



5 



n 



300 



14080 







619 



416 



350 



14050 



14154 







448 



221 



6 



u 



683 



514 



474 



225 



292 



6 



« 



543 



334 







732 



593 



570 



368 



414 







610 



432 



7 



a 



770 



650 



641 



473 



506 



1 



u 



659 



513 







8ol 



696 



695 



558 



585 







699 



584 



8 



t< 



825 



731 



738 



620 



646 



8 



a 



727 



636 







845 



761 



772 



670 



696 







751 



676 



9 



i> 



861 



784 



798 



706 



736 



9 



u 



770 



705 







875 



8ol 



819 



735 



770 







785 



728 



10 



u 



885 



816 



835 



759 



795 



10 



a 



800 



747 







895 



829 



850 



780 



818 







811 



761 



11 



a 



9()3 



840 



862 



798 



837 



11 



a 



821 



772 







HI L 



850 



872 



812 



851 







830 



782 



12 



u 



917 



858 



880 



824 



867 



12 



a 



838 



790 







923 



865 



887 



835 



879 







844 



797 



13 



it 



927 



872 



893 



844 



889 



13 



a 



850 



803 







932 



877 



899 



852 



899 . 







855 



809 



14 



a 



937 



882 



904 



859 



907 



14 



a 



859 



813 







940 



888 



908 



864 



915 







864 



818 



15 



a 



944 



891 



912 



869 



921 



15 



a 



868 



821 







948 



895 



915 



873 



928 







872 



825 



16 



a 



951 



898 



919 



877 



933 



16 



a 



876 



828 







9*3 



901 



921 



880 



939 







880 



831 



17 



a 



956 



904 



924 



883 



945 



17 



a 



882 



834 







961 



908 



927 



885 



950 







885 



837 



18 



u 



964 



911 



929 



887 



954 



18 



a 



887 



840 



