The investigation, of which this paper contains the first part, was undertaken with the view of throwing light on the constitution of salts of trimethl-sulphine.

These salts have been represented in two different ways—1st, as compound of tetratomic sulphur, and 2d, as molecular combinations of sulphide of methyl with methylic ethers, just as the ammonia salts have been represented as compounds of pentad nitrogen, or as molecular combinations of ammonia with hydric salts.