592 Proceedings of Royal Society of Edinburgh. [sess, 
14. With pure sulphur, freed from sulphur dioxide by recrystal- 
lisation or by treatment with carbon dioxide above 310°, or by 
treatment with ammonia or hydrogen sulphide at any temperature 
at which it is fluid, the reverts so rapidly to the soluble form 
that it cannot be supercooled. When traces of sulphur dioxide, 
iodine, and other substances are present, is more or less com- 
pletely supercooled and gives amorphous sulphur. The way in 
which the latter class of foreign substances produces this effect 
is still being investigated. 
15. There is a close analogy of these phenomena to those 
observed in the cooling of cast-iron and steel. 
(. Issued separately April 18 , 1905 .) 
