NITROGUANIDINB 10633. The effects of 36 other inorganic salts, acids and bases have been studied. Salts and oxides of elements of the transition series had various degrees of promoting power. All alkalies accelerated the reaction. Mineral acids had little effect.4. The effect of some substances on the promoting power of ferrous chloride was examined. Large amounts of hydrochloric acid diminished its effectiveness. Sodium nitrate and sodium chloride had very little effect on the acceleration produced by the ferrous chloride, but the latter caused the reaction to proceed slowly beyond the alcohol stage to the hydrocarbon. Sodium nitrite caused a large increase in the induction time and slightly repressed the main part of the reaction.5. Whether a promoter was present or not, and regardless of the nature of the promoter, the first product of the reduction of the aldehydes appeared always to be almost exclusively the corresponding primary alcohol. The formation of hydrocarbon was sometimes observed as a subsequent reaction, but it was always very slow.6. Hypotheses which might account for the mechanism of the promoter effects observed are discussed.