28 



M. H. F. WILKINS 



however, not satisfied with the present state of the X-ray analysis. The 

 difference synthesis should have almost zero amplitude whereas in fact 

 appreciable amplitudes are present. These are presumably due to errors 

 in X-ray intensity measurements and errors in estimating the position of 



.20^ loLtfcr hr>e. 





Fig. II. X-ray dillraction phcjtoKraph (with Mr. X. E. Chard) of lithium salt 

 of DXA showing layer lines to the 20th. The diffraction corresponds to spacings 

 extending down to i -7 A. 



water molecules in the structure. Use of X-ray data of higher resolution 

 would make the errors less important and give further confirmation of the 

 correctness of the structure. Fortunately we have recently been able to 

 obtain data of higher resolution, all layer lines to the 20th (1-7 A) being 

 observed (Fig. 11) and also an isolated reflection on the 30th layer line 



