The well-known Licht-Stechert's viscosity formula¹⁾ gives big errors when it is applied to organic gases at temperature above 100°C or to gases which exhibit association effect, of which a report was made in the author's former paper? (Table 5) Neither can the Hirschfelder's formula²⁾ be available for organic gases at above 130°C or for gases which exhibit large association effect. (Table 5) The Uyehara-Watson method³⁾⁴⁾ also fails to be effective for the organic gases at above 130°C (Table 5). The author obtained several viscosity formulae which held good for organic gases. It was, however, difficult to find a single formula for all the organic gases, which, therefore, were classified into two groups, B and C. Several formulae (A-C2) respectively suitable for each group in the temperature ranges of 0-100°C, 100-300°C, and 300-600°C were derived.
Uses of these formulae are shown in Table 2.
The errors of these formulae are less than 4.5% (in many cases, <3%)
The best method to get viscosities of C group gases at above 100°C is as follows. μ₁₀₀ (the viscosity at 100°C) was obtained by the application of Uyehara-Watson method, and using the μ₁₀₀ values, the viscosities at above 100°C were calculated by means of the author's formulae B1 and C₂.

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I Crushing was accomplished by a drop-weight crushing apparatus with a plunger. The residue of the crushed products R is given by the eq. (1), in which n is the characteristic value of the material, not influenced by the size or shape of the material, so long as it is crushed with the impact or non-impact compression. The authors have not been able to find and distinct relation either between n and the mechanical properties of various materials or between R any Mohs' hardness, compressive strength etc. The relation between residue and weight of cubic or powdery sample is represented by the eqs. (2) and (3). The relation between residue any the condition of load application is given by the eqs. (5) and (7). In the author's experiment of non-impact compression, breaking strength, deformation, Young's modulus, strain energy to fracture, residue of crushed products and n were constant for various compressive speed, and n showed the same value as in the case of impact compression.
II Crushing was accomplished by an apparatus without any plunger as shown in Fig. 7. The residue was also calculated by using the same eqs. (5) and (7). Fracture rate P in percent was obtained by the application of eq. (10). The condition of load application under which fracture occurred is represented by the value of y=Aσ/cσ₀ in the eq. (9), but not by the potential energy A only. Under the condition of constant residue or constant fracture rate, the authors recognized that energy A decreased in spite of the fact that σ/σ₀ increased. In the experiment the energy to fracture in non-impact compression seemed to be rather smaller than that in slow-impact, but larger than that in fast-impact.

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Dust sampling is important for studies on dust flow and air pollution, and many types of dustsamplers have been used in industry. But these samplers are often used under incorrect conditions.
The author made a new dust sampler of filter type, modifying an English mine type, and testedit under various conditions. Fig. 1 shows the sampler, and Fig. 2 an experimental apparatus.
This sampler has two merits as follows.
1) We can make an isokinetic (correct) sampling by equalizing the static pressure P_i at the in-let and the static pressure P_s in the outside flow. (Fig. 3)
2) We can determine approximate quantities of suction flow and dust concentrations by measur-ing pressure drops of cylindrical filter papers. (Fig. 4) Its maximum error is about 30%.
Other experimental results are as follows:-
a) Collection efficiency of the filter paper is almost 100% (complete) even for the finest talc powder.
b) This sampler can give a correct dust distribution on a cross section of dust flow. (Table 2)
c) Dust concentrations, which are tested repeatedly with this sampler at the same position in the dust flow, show good relative consistency. (Table 3)
d) Anisokinetic sampling results in tremendous errors when it is employed in determing dust concentration, the sampled dust weight and the dust fineness (specific surface). A rough tendency can be obtained only by the equations (1)-(5). The relation between the ratio of sampled dust weight G/G₀ and the ratio of suction flow velocity U/U₀ is quite different from that between the ratio of sampled dust concentration m/m0 and the ratio of flow velocity U/U₀. (Fig. 6-8 and Table 4)
More research with detailed experiments must be conducted to determine additional characteristics of this sampler of filter type, which must be approximately equal to those of an inertia dust separator.

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