‘Why didn’t he come over here?’
‘He met with an accident,’ said Marston, laughing. ‘He was shot in a drunken row. It was by the merest fluke that I got to know this process. I thought it might be useful some day.’
‘But I don’t quite see the use of it,’ urged Mr. Brooks, still gazing anxiously at the apparently unsigned cheque.
Marston took it from him, and drew from his pocket a little box containing a fine white powder. This powder he spread over the lower part of the cheque till it completely covered it.
He left it so for a few minutes, then he took the cheque up and emptied the powder back into the box passing his fingers carefully down the paper to see that not a grain remained.
‘Now look at it,’ he exclaimed.
Mr. Brooks did look, and he was delighted at what he saw.
A faint violet signature was at the bottom of the cheque. It was perfect. Every dot, every line.
‘I guess the rest,’ he said. ‘Any special ink wanted?’
‘None,’ answered Marston. ‘Fire away.’