Hank site, a new Anhydrous Sulphate- Carbonate. 



239 



ably and generously gives to science. The crystals sent being 

 quite clear, Dr. Dana was, in a few days, enabled to report them 

 "as uniaxial (double refraction negative) and that normally," 

 and thus their positive difference from Thenardite was proven 

 beyond question. They were irue hexagonal crystals. Believing 

 now the mineral to be either a dimorphous form of sodium sul- 

 phate, or possibly an entirely new species, an analysis seemed 

 necessary. Accordingly I placed sufficient material in the hands 

 of Mr. James B. Mackintosh, E. M., for that purpose, and he 

 has very kindly done the work. His results showed the mineral 

 to contain the following substances : 



S0 3 - - - 45.89 



CO, - - - 5.42 



CI. ... 2.36 



*Na„0 - - - 46.34 



Corresponding to 





Na 2 S0 4 - - 



81.45 



Na, CO, - - 



- 13.06 



NaCl - 



3.89 



Na 2 (excess) 



- 1.08 



99.48 

 These results give the following molecular ratios for 



Na 2 S0 4 

 Na 2 CO, 

 NaCl 

 Na. 



57.3 

 14-5 

 6.65 



1 

 I 

 \ or 



3.95 



1.00 



.46 



.12 



Or closely in the ratio of 4 : 1 : -^ : \. 

 mula. 



1.74J 



This all points to the for- 



4 (Na 2 S0 4 ) + 1 (Na 2 C0 3 ) + \ (Na CI) 



as representing the composition of the crystals under examina- 

 tion. Or, neglecting the sodium chloride as non-essential, the 

 formula could be given thus : — 



4 Na 2 S0 4 + Na 2 CO a 

 which is probably the true one. 



All bases calculated as soda. Lime and magnesia were not present. 



