The increase in demand for energy, coupled with an increased concern for environmental quality, has developed a real shortage of natural gas and induced shortage of petroleum.
From the necessary of clean gaseous and liquid fuels and electricity from coal, the researches and developments as the national projects have begun.
Review was made on clean fuels from coal at the political and technological view points.

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By an experimental reappearance of the crooked-hole phenomenon of a deep boring, a series of the studies concerning the investigation of the influences of possible causes on a crook has been proceeded by authors. As a part of the above. the mechanism of this crook of a borehole and the influence of the circulating rate of water on it are described in this paper.
An artificial rock sample having the inclined boundary of two layers of different strengths caused by the ratio of the content of cement and the pulverized limestone was made, and it was drilled with the non-coring metal bit of 36mmφ, 9mm in length set to the rod of 10.5mmφ, 2000mm in length, in this experiment.
Consequently, it was proved that to produce the crook of borehole was possible by the drilling of a short, borehole even the length within 300mm and the deviation of the borehole to the direction of “up-dip” side occurred after shifting to that of “down-dip” side primarily. And, according to the increase of the wearlands of tips of the bit, it was found that the more the circulating rate of water raises the smaller the degree of the deviation of the borehole becomes.

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Study of Non-Newtonian flow, especially, flow of Bentonite slurry is applicable in the drilling of oil wells. Analytical solutions for the power law fluid in an axial annular flow have been given by Fredrickson and Bird. But it was pointed out by Vaughn and Bergman that the results of the analytical solutions were not agreement with the experimental results in annuli.
In this paper, it was ascertained that the parameters in a power law model which were determined by a “combinations theory” proposed by the authors were useful and the equations showed by Fredrickson and Bird were enable to calculate the relations between the flow rate and the pressure drop in annuli, and the authors, also, could define the new modified Reynolds number, as follows, for the power law fluid such as Bentonite slurry in annuli.
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where, f=friction factor, Rep=new modified Reynolds number, D₀=diameter of outer tube of annuli, κ=ratio of radius, ρ=density, V=mean velocity in annuli, ΔP=pressure drop, L=length of annuli, K=fluid Gonsistency index, n=flow behavior index, Ωp=function of n andκdefined by Fredrickson and Bird.
Further-more, in the case of rotation of inper tube authors measured the pressure drop. As the results, no effects were ascertained about the above-mentioned problems.

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This is the first of a series of papers dealing with the solid-liquid sedimentation phenomena in the hindered settling range.
While the effect of the concentration on the settling rate of fine particles in suspension have been investigated by Steinour, Richardson and Zaki, and so on, the present authors intend to resolve some of the questions stimulated by these previous works.
As an initial step to develop a more complete understanding of the hindered settling behavior in concentrated suspensions of the fine particles, some experimental results are presented for closely sized particles under the condition of laminar flow.
Closely sized olivine suspensions with various initial solids concentrations were made to settle in the sedimentation density measurement apparatus, fitted with aγ-ray densimeter and a lifting device.
And then, from the density curves which were obtained in the way described above, it could be calculated the apparent Stokes diameter x, as well as the cumulative distributionΦ(x) and distribution density function f (x), by the following equations:
x=18η/(ρ_s-ρ_lg·h/t)^1/2…(1)
Φ(x)=C/C₀=∫₀^xf(x)dx…(2)
f(x)=-(2t/x)·dΦ(x)/dt…(3)
Authors obtained the relations between the characteristic values of the distributions and the solids concentrations to be interpreted in terms of the hindered settling behavior of particles.
Authors also attempted to approximate the apparent distribution curves using these characteristic values.

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The potential and pH measurements of the Fe-SO₄-H₂0 suspension system were carried out at 90°C by increasing the pH of sulfate solutions containing sulfate ion of around 1 mol/lby the aid of a rotating Pt electrode, a glass electrode, and two reference electrodes.
Theresultsobtainedare summarized in the potential-pH diagram (Fig.6 in the text) including the stable regions of Fe⁰ (powder), Fe²⁺, Fe³⁺, basic ferric salt, ferric oxide hydrated, basic ferrous salt (Fe₂ (OH) ₂SO₄) ₈ and ferrous oxide hydrated. Empirical potential-pH equations are also presented and compared with those calculated at 100°C.

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