118 M. Scheerer's Observations on Elceolith and Nepheline. 



The mineral might therefore be regarded as consisting of 

 1 atom soda elaeolith (according to the older formula), and of 

 1 atom calcareous spar, and should have the following com- 

 position : 



Silica . 

 Alumina 



Soda . 

 Lime . 

 Carbonic acid 



38*23 



31*89 



19*41 



5*89 



4-58 



10000 

 But if my formula be adopted as the correct one for elaeo- 



lith, cancrinite would be expressed by the formula Na' 2 Si 



+ 2 Al Si + Ca C, and calculated accordingly, should have 

 the composition : 



Silica 39-11 



Alumina .... 28*98 



Soda 17*65 



Lime 8-03 



Carbonic acid . . 6*23 



10000 

 A more satisfactory agreement of the formula with the com- 

 position found can scarcely be expected in analysis. They 

 appear merely to differ in the formula giving the amount of 

 lime about 1 per cent, higher 5 but this difference disappears 

 almost entirely if we admit that the potash replaces a portion 

 of the lime. That lime and potash replace one another 

 is evident from the analyses 10, 11, and 12 of nepheline. 

 This latter is, indeed, only essentially different from the other 

 elaeoliths by the greater quantity of lime it contains ; but it 

 seems that principally the amount of potash has been dimi- 

 nished by its occurrence, while the soda does not at all differ 

 in proportion. Cancrinite, therefore, actually contains 1 at. of 

 nepheline of a composition, such as was formerly adopted 

 for the Vesuvian nepheline, but which has hitherto not been 

 found in an isolated mineral. 



On closer consideration, it will be found that the cancrinite 

 affords even a better test for the correctness of my formula 

 than the elaeolith itself. The atomic value of the elaeolith, 



according to the older formula (if we add 4 Si, 3 Al, 2'4 Na, 



and 0*6 Ka together), equals 5529, according to the new 



one (if 3 Si, 2 Al, 1-6 Na, and 0'4 Ka are added) = 3877. 



