In the previous reseaches we had found that this meter had many good points for the automatic indicator or controller of the concentration, but in the present stage of the developments it had several week points, such as the non-linearity of the response-curve and the limitation in the applicable range of concentration.
In this paper we aimed at the improvements of such inferior properties and experienced using the HCl and KOH aq. the relations between the response-curve and the B-voltage, Pt-wire insersion effect, the methods of measurement as well as the shape and size of cells.
The results obtained were shown in Fig. 3-14 as well as Table 2 and 5.
From the experimental results we concluded that:-
(1) Increasing the B-voltage, the output current and sensibility of the response-curve increased not to sacrifice the stability of current.
(2) Increasing the linearity of the frequency-output current curve, the linearity of the responsecurve will be extended to the higher concentration range.
(3) By the profitable selection of the shape and size of cell condensor and the method of measurement, the desirable response-curve answered the purpose will be obtained.

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Based on the consideration of intermediate state called "Fluidized Beds", an attempt has been made to represent the fluid friction through fixed beds by the drag coefficient of a single particle. This is because the beds of solid particles change from fixed to fluidized state, with the increase in velocity of upward current, until they disppear in pneumatic transporting suspensions.
The critical velocity where the fixed beds begin to fluidize, u_mf, is described in the author's previous article¹⁷⁾ as independent of the shape of particles or to the voidage of the beds as expressed by Eq. (1). Can the shape and voidage term, then, be eliminated in the same way from the equation of fluid friction through fixed beds? Empirically, the pressure drops in fluidized beds are nearly equal to the density difference of solid and fluid.^{9), 11), 12)} To apply Eq. (1) to the ranges of velocities lower than u_mf where the solid beds do not fluidize, an attempt is made to substitute the density term of eq. (1) for the pressure drop term of Eq. (2). Then, the pressure drops through loosely packed beds before fluidization can be expressed as Eq. (8), in laminar region, without using the shape or voidage factor of solid particles.
Experiments are made with the apparatus as shown in Fig. 1, and it is found that the data of the friction factor f_v" defined by Eq. (8) are nearly constant -about 600- in laminar region. When E_q. (8) is further applied to the transition or turbulent region, the values of f_v" remain no longer constant but increase with the increase in fluid velocity or the modified Reynolds' Number, Rep, as shown by curve AB in Fig. 2. The values of f_v" for irregular particles are slightly greater than those for smooth spheres in Fig. 2. Recalculated results from literature data are also shown as a comparison in Table 1 and Fig. 3.
Pressure drops in fluidized beds are independent of the fluid velocity and remain nearly constant as indicated in Eq. (2). From Eq. (8), with the help of Eq. (2), the friction factor f_v" for fluidized beds is derived which is found to be inversely proportional to the fluid velocity or the modified Reynolds' Number. The results are shown by the straight lines of AC, BD, etc. in Fig. 2. When the fluid velocity is a little higher than the terminal velocity, ut, of the individual particle, all solids are transported by the fluid stream and the fluidized bed disappears. Then, instead of Eq. (8), E_q. (10) becomes applicable to the single particle. The curve CD in Fig. 2 shows the experimental data of f_v" for single particles as the limits of the fluidized beds.
In the case of irregular particles generally used, the values of f_v" are slightly greater than in that of smooth spheres (dotted line in Fig. 2), similar to the case of fixed beds. From E_q. (10) and E_q. (11), we can derive f_v" as follows: 2f_v"=(3/4)C_DRe_p…(12) for the terminal velocity of single particles. Likewise, from E_q. (12), a constant value of 2f_v"=(3/4)×24=18 can be obtained for smooth spheres, in laminar region.
The above description may be summarized as follows:
a) f_v" in fixed beds, Eq. (8), varies along the curve AB with the increase in fluid velocity untill fluidization begins at umf [c.f. E_q. (1) and (2)].
b) In fluidized beds, f_v" decreases inversely proportional to the increase in fluid velocity along the straight line AC or BD.
c) Fluidized bed disappears at the point where either AC or BD line intersects the curve CD of single particles.

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The theoretical solution of the coefficient of heat transfer by cooling or heating (without change in phase) of a Newtonian fluid in laminar flow have already been proposed by Graetz, Nusselt, etc.
Referring to those solutions, the author has tried to solve the heat transfer in laminar flow of a pseudoplastic fluid. Hasegawa has found that the velocity distribution of pseudoplastic fluids flowing in a tube can be represented by the following equation
by making use of which, the author has obtained the approximate solution for pseudoplastic fluids as follows:
provide,
The author's theoretical solution has been further developed into
in which, when n=2, the numerical calculation is as follows:
The curve n=2 in Figure 3 shows the theoretical relation of (h_MD/λ) plotted as ordinated against (WC_p/λl). The curve n=∞ shows the theoretical relation based on a rod-like flow, and the curve n=1, a Newtonian fluid. Based upon the theoretical and approximate solutions, it is to be found that (h_MD/λ) of a pseudoplastic fluids is in the zone where the curve n=∞ is lines superior and the curve n=1 is lines inferior.
Hence by the approximate solution, the author has rearranged (WC_p/λl)as{(WC_p/λl)(n+3)/4}. The theoretical relation may be represented by
The author has found that the logarithmic mean of the temperature difference between the bulk temperature of a fluid and the temperature of the wall is theoretically correct. The temperature profiles in the case of (WC_p/λl)<0.1 are shown in Figure 5.

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