Water and Ammonia in Zeolites

Tiselius (5,6) found that the double refraction of light by these crystals was dependent upon the extent of hydration of the lattice. The crystals were cut for this purpose in the form of thin plates, and the rays were examined in a polarisation microscope. As a first approximation, Tiselius then considered Fick s law to hold. To interpret his data he used 

For this solution of Fick s equation the boundary conditions 

The equation provides three methods of obtaining D, the diffusion constant, which are  

All three methods were employed successfully in Tiselius s experiments. 

The laminated lattice of heulandite has the laminae parallel to the 010 plane. The diffusion of water normal to this plane was found to be Doio 7 x lO- cm. sec. at 20 0. but diffusion of water parallel to the 010 plane was rapid, though 

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