Recently, an optimum reaction temperature has been studied concerning the operation of the most efficient reactor, both in theory and practice.
One of the practical approaches to it is through the observation of operations of a multistage reactor provided with an internal cooling system. In this paper, the writer is going to give conditions necessary for obtaining the greatest efficiency from such a multistage reactor.
These conditions are
1.In-every partl react pertaining to the mu1tisge OperatiOn, the integra1 ∫∂(1/r)/∂T dx must be zero.
2. The reaction rate at the outlet of the i-th partial reactor must be equal to the rate at the inlet of the (i+1) th partial reactor.
The above may well be regarded as sufficient and necessary conditions for the purpose, and at the same time worth considering when designing multistage reactors, although under some restrictions.
Applying the theory to the water-gas-shift reaction, the writer has drawn some conclusion.

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The gas absorption rate of carbon dioxide by a forming droplet of water was experimentally studied, using the glass nozzles as shown in Table 1, in the range of drop formation time 0.5-6sec. and temperature, 20-50°C. And the experimental results obtained were considcred from the from conditions of the droplet and compared with the data on liquid jet.
The data on droplet were correlated by the following experimental equations.
In the range of drop formation time below 3sec., and above 3sec.
Further, the data on liquid jet were correlated by the following equation

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In the recent years, several types of mixers such as V-, double-cone=(DC-), and cubio-type (C-), have been introduced for mixing of powders but their experimental data are little available.
In our previous paper, we made a report on our researches in the operation of the V-type mixet. The present paper deals with Our continude studies in the descrided above in the process of mixing and the optimum operating conditions for the mixers described above and a horizontal cylinder-type mixer, as well. The experiments were made in mixing two kinds of dry powders, Na₂CO₃-polyvinyl chloride, having the same particle-sized distribution, with a view, among other things, to obtaining standards fur the selection of the type of mixers serving one's purpose.
What were made clear by our researches are:
1) The process of mixing is similar for all types of mixers as shown in Figs.2, 3 and 4, except for the part in the initial period, logσ vs. Nθ, where curves are linear. All the curves have the minimum values of σ, σs throughout the rest of the mixing process θ_s.
2) The number of the revolution of the mixer (Nθ)_s and the minimum standard deviation σ_s in the best mixing state vary with the types of mixers as shown in Figs.5 and 6.
3) Some of the mixers (e.g., DC-& HC-type) which have smaller values of (Nθ)_s have larger values of σ_s, and others (e.g., C-& V-type) which have smaller values of σ_s have larger values of (Nθ)_s as shown in Table 2.
4) The optimum volumes of powder chargeable are similar for all types of the mixers, but the effects of the charged volume on (Nθ)_s and σ_s are different, as shown in Figs.7 and 8.
5) The results shown in 3) and 4) may serve as standards for the selection of the types of mixers which one wants to use.

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Department of Chemical Engineering, University of Tokyo, Tokyo Moisture distribution in columns, 40mm square ×1m high, (Fig.2)of similar sized sand and uniform glass, respectively, have been studied. The schematic diagram of the moisture distribution. (Fig.3) shows that there are three zones in each of the columns: viz., saturation zone, low-moisture zone and transition zone. For theoretical consideration it may be convenient to express the moisture content in terms of the degrees of saturation, that is water volume per unit pore volume.
The height of the saturation zone (h_s) is generally well approximated by Eq. (5), which is based on the assumption that the bed is equivalent. to a group of capillary tubes with variable diameters as shown in Fig. 5 (5).
In the low-moisture zone, the moisture of the bed is found to consist of two parts, viz., the moisture retained as a wedge (S_w) and the surface. adhering moisture (S_a). When the spheres of the bed are large enough, the surface-adhering moisture is negligibly small and the volume of wedge moisture for glass spheres of several different diameters can be calculated by means of Eq. (10) into which has been introduced N derived from Eq. (11). S_w is available in the calculation of the angle θ(Fig.7) by means of Eq. (8) as shown in Table 3. The quaatity of the surface-adhering liquid can be determined from Eq. S_L=S_w+S_a because the value of S_w is independent of the particle size (Eq. 12). By introducing θ=27° into Ep. (8), S_a and S_w of rbeds of relatively small particles may be presented as in Table (4), which shows the thickness of the layer of the surface-adhering liquid, as well, assuming that said liquid spreads uniformly over the surface of particles. It is interesting to note that in these cases, S_a exceeds S_w even by a thin film of about 2 microns,
Section 6 shows some of the Gillmore and Wright's results to which may well apply the equations mentioned above.

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