It has been found out that phosphate glasses strike into reddish-orange or reddish-brown by heat treatment above approximately 600°C if they are previously melted under strong reducing conditions made by using ammonium phosphate asraw material or by adding reducing agents such as metallic silicon, graphite, or starch to the glass batch.
In the present study, the necessary condition for obtaining phosphate glass having the possibility of striking, the chemical detection of the coloring matter in glass, measurements of the light absorption characteristic of the glass, and electron microscopic examinations were carried out. Based on experimental results, it has been confirmed that the essential substance of the coloring matter in the struck glass is red or scarlet phosphorus contained in the glass as numerous colloidal particles.

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Thermal state in electric arc furnace in which many refractory materials are melted has not yet been clear enough to control melting process completely. This work deals theoretically with temperature distribution in the furnace using a simple model based upon experimental data.
The furnace shape is modeled as a spheroid having an isothermal surface with temperature θ_s. In the furnace, closely packed test specimen is heated by a heat source that locates on a straight line of segment limiting the both foci of the spheroid. Distribution of generated heat energy in the source is derived from a power density function, P(x′), that depends upon coordinate x′ set along the heat source and is normalized to supplied electric power P.
∫P(x′)dx′=P…(1)
Therefore a heat element generated in an elemental length of the heat source, Δx′, is P(x′) Δx′ which flows out through the specimen in all directions uniformly.
The furnace is assumed to be kept in thermally stationary state with heat transfer depending either on thermal conduction in the furnace or on thermal convection on its surface. If the heat source consists of only one element, temperature at any point in the furnace Δθ is virtually given in the following equation,
d²Δθ/dγ²+(2/γ)dΔθ/dγ=0…(2)
where γ is radius vector of any point from the element of the heat source. Heat flowing per second through a spherical surface having a center in the element of the heat source has to be tantamount to heat generated per second, then
4πγ²λ⋅dΔθ/dγ=P(x′)Δx′…(3)
where λ is thermal conductivity of the specimen in the furnace. And the temperature of outer shell of the furnace is virtually Δθ_s at any point having a radius vector R.
Δθ=Δθ_s at γ=R…(4)
Solving equation (2) under boundary conditions consisting of equations (3) and (4), virtual temperature is given as follows.
Δθ=Δθ_s+P(x′)Δx′/4πλ(1/γ-1/R)…(5)
As any point in the furnace receives heat energy from every element of the heat source, it is necessary for obtaining real temperature to superpose all virtual temperatures of that point. Using a rectangular coordinates, (x, y), in which the origin and the abscissa are common with those in the coordinate (x′), real temperature θ_ij at the point x_iy_j is obtained by integrating Δθ_ij over all range of the heat source, as follows:
θ_ij=θ_s+1/4πλ∫_-k^kP(x′){1/γ_ij-1/R_IJ}dx′
=θ_s+1/4πλ∫_-k^kP(x′){1/√y_j²+1/(x_i-x′)²-1/√y_J²+(x_I-x′)²}dx′…(6)
where k and -k are coordinates of both ends of the heat source and x_I and y_J are coordinates where isothermal curve (x²/a²+y²/b²=1, a and b are half length of major and minor axes of the isothermal

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In glass-forming oxide systems without modifier ions, network structures are not broken anywhere, and these glasses must be different in their properties from usual glasses which contain some modifier components. In the glasses of the GeO₂-B₂O₃ system we measured several properties: the thermal expansion, the deforming temperature, the density, the refractive index, the viscosity, and the infra-red absorption. The results of our measurements are shown in Figs. 1-6 and Fig. 11. We can see, in Figs. 1-4 and Fig. 6a, one or two bending points in every curve showing the relation between the composition and the property. The composition of the first point is about 85 cat.% of B₂O₃, while that of the second point is about 50 cat.%. The latter point appears similarly in every curve; it is assumed that the reason for the appearance of the latter point is a packing effect of two kinds of balls with different radii.
The first point appears clearly in the curve of the expansion coefficient, which resembles that of the SiO₂-B₂O₃ system. Accordingly, it is considered that the appearance of the first point is due to an effect of the 4-coordination structure, which interferes with the thermal expansion effect of the 3-coordination. structure. If it is assumed that the interference of the 4-coordination acts not only on the oxygens connecting with the 4-coordination ion directly (marked _??_ in Fig. 7), but also on the next oxygens beyond B (marked _??_), this effect reaches a maximum at 13.04 cat.% of the 4-coordination component and becomes zero at 42.85 cat.%. We can then represent the expansion coefficient of these systems by the following equations:
x=0.0000-0.1304
α=α_IV⋅x+(1-x)α_B-4(γ+2δ)x
x=0.1304-0.4285
α=α_IV⋅x+(1-x)α_B-4γx-(1.5-3.5x)δ
x=0.4285-1.0000
α=α_IV⋅x+(1-x)(α_B-3γ),
x=4 cat.% fraction of the 4-coordinate component, α=the expansion coefficient of glass, α_IV=the expansion coefficient of the 4-coordinate component, α_B=the expansion coefficient of B₂O₃.
B₂O₃-SiO₂ system: γ=2.6, δ=2.9
B₂O₃-GeO₂ system: γ=2.5₃, δ=2.0
In connection with above things we considered the problem of boric acid anomaly in the B₂O₃-R₂O system (R=Li, Na, K). According to the above results, a bending point must appear at the constant place (Fig. 8), even though the 4-coordination of B increases continuously with the quantity of R. However, the minimum point of the expansion coefficient of these systems depends on the kind of alkali ion. Therefore, the reason for the increase in the expansion coefficient beyond the minimum point is the decrease in the hole radius of the polygonal ring; this shrinkage is caused by the increase in the 4-coordination structure (cf. Fig. 9 and Table 1). The shrinkage of the hole results from the repulsion of the alkali ion or from its exclusion from an intersticial hole.
We then studied the expansion coefficient of the B₂O₃-GeO₂-Na₂O system. The results correspond with the calculated values assuming the preferential 4-coordination of B (marked in Fig. 10), and does not correspond with the values assuming that of Ge (marked _??_). The addition of the 4-coordination of Ge causes shrinking of the hole, but it does not cause the repulsion of the alkali ion. Accordingly it is assumed that the increase in the expansion coefficient beyond the minimum point arises from the replusion of the alkali ion.
We also studied the

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