Salithion rearranges thermally into two kinds of isomers, S-methyl-salithionand Sbenzyl-salithion, which generate, by further heating, corresponding sulfides such as gaseous dimethyl sulfide and benzyl sulfide derivatives. Thermal degradation of salithion in a closed system proceeds more easily than that in an open system. It was found that these sulfides catalyzed isomerization reaction, and dimethyl sulfide was more effective. Autocatalytic degradation mechanism in which dimethyl sulfide gas is produced from S-methyl-salithion, plays the most important role in a closed system. Successful methods to stabilize salithion against thermal degradation are shown. Their properties are discussed on the basis of their assumed mechanism of stabilization.(i) Storage in a paper bag rather than in a gas-barrier film is suitable, possibly as a result of reduction of dimethyl sulfide accumulation. (ii) Inclusion with fl-cyclodextrin is also effective to hinder bimolecular reaction of salithion to produce isomers. (iii), l-Naphtylphenylamine, a stabilizer of salithion, is assumed to be a scavenger of the isomers, which are sources of the active sulfides.

The suspension stability of two mineral carriers were investigated in various hard water with or without surfactants. As the hardness of water increased, the suspensibility of kaolinite clay decreased because its primary particles coagulated due to the lower 0-potential.However, an addition of sodium dodecylbenzene sulfonate to kaolinite clay effectively raised the suspensibility by providing high c-potential to particles. On the other hand, the suspensibility of diatomaceous earth was lower with the surfactant than without, while the c-potential was higher with it. The adhesion tension of diatomaceous earth was reduced by the surfactant, while that of kaolinite clay was raised by it. This suggested that the surfactant raised the interfacial energy of diatomaceous earth, causing coagulation occurred.The difference in the effect of surfactants on the adhesion tension between diatomaceous earth and kaolinite clay seemed to come from the difference in the hydrophilicity of their surfaces: the former had relatively high affinity for water, while the latter was hydrophobic.

S-3552 has low solubility in organic solvents usually used as solvents for EC formulation. Therefore EC whose a. i. content is lower than 20% is only formulated with xylene and isophorone. Herbicidal activity of EC formulation, however, is superior to those of Flowable and WP formulations. Therefore increase of content of S-3552 in EC formulation is tried. It was found that S-3552 could be formulated into 30 EC formulation by using phenol as a cosolvent and choosing proper emulsifiers, which gave good low temperature stability, emulsion stability and storage stability. It also showed herbicidal activity as good as 10 EC and 20 EC of xylene/isophorone solvent.