(1) Empirical formula for the power requirements of paddle agitators which are settled in the centre of cylindrical vessels filled with water, has been determined as follows:
where: P=power absorbed by agitators, D=tank diameter, H=liquid depth, n=shaft speed, d=paddle diameter, h=paddle width, θ=blade angle to the horizontal plane, ρ=density of liquid, all in consistent units.
(2) In the eccentric locations beyond half the paddle diameter (θ=90° agitator), the power requirement reaches to a maximum value (P_max.) as follows:
(3) The correction formula for the viscosities was also determined.
(4) The maximum powers (P_max.) are independent on liquid viscosities, and therefore the same equation as (2) can also be applied for viscous fluids.

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Hixson and Baum's data (Ind. Eng. Chem., 33, 478 (1941)) on the rate of solution of solids in liquids were corrected, and the following results were obtained.
(1) Hixson's general equations are erroneous, because they have overlooked the particle size, the particle density and the gravity constant.
(2) The larger the difference in densities between two phases, the greater will be the effect of agitation for the reduction of film resistance.
(3) It can be concluded that, in the solid-liquid reaction systems, the object of agitation will be in the decrease of the diffusion film resistance above a certain range of agitator speed and in the liquid-liquid reaction systems, it will be confined chiefly in the increase of reaction area and very little effect can be expected in the decrease of the diffusion film resistance.

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The efficiencies of injecters, with different sizes of the diffuser diameter and different distances between the nozzle and the diffuser, have been mainly studied. From these experimental data, the authors have tried to establish how to design injecters from the technical stand-points. Some conclusions have been gained as follows.
The optimum condition is
where, ε: The square of nozzle to diffuser diameter ratio.
μ: The driven to driving flow-rate ratio.
α: The driven to driving gauge pressure ratio.
m: The corrective factor regarding to distance between nozzle and diffuser.

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