This paper describes some experiments with the vibration behaviour of the granular materials. The acceleration and the displacement are measured concerning the screened sand (diameter: 0.8mm) which slides repeatedly on the vibrating trough (the frequency: f=10-15Hz and the amplitude: a=2-4mm). The results of the experiments and the considerations are as follows:
(1) The vertical acceleration of the granular materials ÿ varies almost as: 0g→-0.5g→0g→0.7g→0g instantaneously when the sliding direction changes (g is the acceleration of gravity).
(2) The grains move vertically each time when the sliding direction is reversed. Therefore, the vertical motion repeats with a half of the period of the trough.
(3) This phenomenon is considered to be caused by the rearrangement of the grains with the repeated sliding.

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It has been already reported by the authors that the vertical pressure distribution of granular materials are very complicated according to the local arching in the bed caused by both internal and wall friction.
Continuously the authors measured on the vertical pressure distribution of the bed mixed with the fine powder and granular materials to ascertain the real facts of the arching in the bed, and considered in addition to the previous report.
As the results, it is found out that the vertical pressure of the bed mixed becomes considerable higher pressure than that of the bed of granular materials only. These reasons are explained by the change in physical properties of the bed mixed; caused a decrease of internal friction and an increase of apparent density.

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Measurements were made of the particulate concentration and size distributions in an air-talcum suspension across a horizontal circular duct downstream of a venturi. A cascade impactor was used for the determination of concentrations and size distributions of dust in small samples of the suspension extracted from the duct.
The experimental results indicated that the particles, like the air velocity, remained uniformly distributed, except for sampling positions immediately near to the wall of the duct, and the venturi was efficient, both to obtain uniform flow, and also to ensure that a dust sample extracted at a single point, near the center of the duct, should be representative of the whole of the suspension. Thus the venturi was suggested to facilitate single-point sampling which was obviously more advantageous than multi-point sampling, from the point of view of ease of operation.
Concerning the size distribution, some interesting performance data were also presented, which confirmed the possibility of using the cascade impactor as an aerosol sizing device capable of giving direct size analysis figures of dust in the dry state.

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