Preparation of Grey Tin

IT is well known that most commercial forms of tin can be transformed to the grey (α) allotropic modification in an ordinary refrigerator by contact with particles of previously prepared grey tin. The difficulty, of course, is to get some grey tin to start with, and we know of many laboratories both in Britain and abroad in which attempts to make grey tin have been unsuccessful. We have worked on various aspects of grey tin from time to time, and, although we are not ready to give a connected account of this work, we wish to record a few of our observations in the hope that they may be helpful to other investigators.