94 The Electron Microscope 



drew attention to the excellent coating properties of chromium 

 and uranium, which form fine, even, structureless layers. A 

 thickness of 5-10 A of uranium is sufficient to give well observ- 

 able contrast. But the most often used metal is gold. Figure 34b 

 is a brilliant example of a gold shadowcast, taken by Crowe and 

 Robinow in the Cavendish Laboratory, Cambridge, England. 



