224 S. L. P enfielcl and G. S. Jamieson— Tychite. 



the crystals were in every respect like those of the artificial 

 northnpite and tychite. As seen with the microscope the 

 crystals were full of inclusions, and, in forming, had evidently 

 enclosed an unusually large amount of amorphous magnesium 

 carbonate precipitate. We assumed at once, and correctly, that 

 the compound would prove to be like north upite and tychite, 

 except in having a C0 3 radical in the place of Cl 3 and S0 4 , 

 namely, 2MgCO, . 2Na 2 C0 3 . J^a 2 C0 3 ; see page 222. The analy- 

 sis, made on a small quantity of the rather impure product, 

 gave almost the theoretical percentage of C0 2 , but the MgO 

 was high and the Na 2 low, which was to be expected. 

 Attempts will be made later to produce this salt in a state of 

 purity, when it will be described more minutely. 



Mineralogical Laboratory of the 



Sheffield Scientific School of Yale University, 



New Haven, Conn., July, 1905. 



