Crushing is accomplished by dropping a steel ball on a plunger resting on the samples (Stoneware) in a steel mortar. The experimental results are as follows:
The residue of crushed products R in percent is given by the equation
(I)
R=f(y) (II)
where, x: particle size in mm
σ: max. stress by eq. (17), e: base of natural logarithm
σ₀: stat. stress by eq. (17), k, n, c: Constants
A: gross work input to crushing in kgm by eq. (15)
Eq. (1) is applicable in the following cases:
1. Free crushing, in which fines 100 mesh minus are removed.
2. Choke crushing, in which, Residue (100 mesh plus)≥75%
Eq. (2) is applicable in the choke crushing, in which, Residue (100 mesh plus)<75%
We have found close similarity between these equations and the corresponding experimental data, regardless of the ball weight or the drop height.
Comparing these equations with those of Rittinger's, we have proved that the former ones are more useful than the latter ones.

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10数種の工業用粉末の粒度を液体沈降法,風篩法およびブレーン比表面積法によつて測定すると,いずれも残滓粒度分布はRosin-Rammlerの式によつて大体表示しうるが,沈降法と風篩法では甚しい相違を示すものがある。また上記の式における指数nは0.2乃至2.4の範囲に変化し,必ずしも1附近の値とはいえない。次はサイクロン集塵器に前記各種粉末を用いて分離効率を求め,近似計算と仮想分離限界粒子径とを用いて粒度分布線図上にサイクロン点を求めると大体風篩法による値に近いか,やや下方すなわち粗粒の側に存在し,サイクロン内の粉末の分散程度は風篩器における値か,それよりやや凝集した状態にあるといえる。これから粉末が違つたときのサイクロン性能の推定がある程度可能である。また比表面積と分離効率とは大体において反比例するが,必ずしも一定の傾向はもつていない.

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Assuming the fracture occurs when the stress is widely over the allowable one, grinding would cease just as the stress arrives at its limit, since it would gradually decrease as the fracture is in progress. As the final value of specific surface of particles S_∞, in the above condition, would depend upon the energy-efficiency, the author proposed the following equation: where K was termed the “Comminution Coefficient.”
Rittinger's and Kick's law and others were approximately explained by the inter-relation of K and S_∞ in this concept.
This equation was verified by grinding tests with frictional forces which took place among particles packed in a steel mortar, and with impact of the drop-weight.
From both kinds of tests for several ceramic materials, it was found out that S_∞ was proportional to 0.4 power of force, and that k_f and k_i Were constants for materials of similar type of force, independent of the numerical value, although dependent upon the capacity.
It was suggested that the ratio of k_f to k_i of each material at the same hold-up would be an important variable in comminution, which was probably fixed according to its inner structure.
The comparison of particle-size distributions of typical samples in both Kinds of grinding was briefly discussed.

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球を粉体層へ落下させて貫入率を測定し,高速度写真を用いてその貫入率と衝撃力との関係を求め,更に球の下面の応力集中係数を理論的に解析して,最大衝撃応力を表わす式を次の如く決定した。
この式によれば,従来ボールミル粉砕に関して得られている経験的事実がよく説明される.

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有名なKundtの実験(1866)により明らかにされた音波の作用による粒子の凝集現象はその後の研究につれてこれを応用した集塵装置の出現をみるに到つた。この間において数多くの基礎的研究が行われてきたが,化学工学的見地よりみれば未だ実験的研究の段階にありこれを定量的に扱つたものは極めて少ない。そこで筆者はこの報告において現在までに知られている基礎的データにもとづいて工業的音波集塵装置の設計根拠を考察した.

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