An examination of the various theories put forward to account for the fungicidal action of sulphur when applied, not to the plant or fungus, but to a heated surface, has been carried out by chemical methods, and it is concluded:

  • 1
     That, since the volatile agent is capable of passing a glass-wool filter maintained at the temperature of the heated surface, it is gaseous in character.
  • 2
     That the removal of the volatile agent by passage through a cooled glass-wool filter is proof that it is neither sulphur dioxide nor hydrogen sulphide but is elementary sulphur.
  • 3
     That the condensation of sulphur volatilised from the heated surface appears sufficient to account for the reactions ascribed to particulate sulphur.