Lignosulfonates as balium salts, separated from a laboratory sulfite cooking spent liquor of beech wood, were fractionally precipitated from aqueous solution by adding ethanol, and the ten precipitated fractions were characterized.
These fractions were analysed for methoxyl, sulfur, acid groups and determined molecular weight distribution. Absorption spectrum analyses showed that the ten fractions were roughly uniform in the ultraviolet and the infrared absorption spectra.
Ethanol fractionation appeared to fractionate the lignosulfonates in solution on the basis of the molecular weight and also the degree of sulfonation. The integral molecular weight distribution plot indicates that the molecular weights of the beech lignosulfonates investigated range from about 1, 000 and 70, 000.

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The measuring method of the wire mark and its quantitative representation were dealt with in a previous paper. In this paper, we discuss the method for evaluating the sheet formation by analyzing the light transmitted through the paper. Variation in basis weight, thickness and density of small cutted disks (0.55cm$oslash;) and their corresponding optical sheet properties were measured. A good correlation was obtained between the optical transmittance and the basis weight variation (γ_T0W=-0.972, γ_T0W·Z=-0.851). From this result, a coefficient of variation of basis weight S_W, which is defined as a ratio of the standard deviation to the mean value of a basis weight can be expressed by the optical quantities as
S_W=S_T0/|lnT₀/1-R_∞²|
were S_T0 : coefficient of optical transmittance variation
T₀ : mean transmittance
R_∞ : reflectance of a layer of infinite thickness
In addition, the auto-correlation function of sheet formation was calculated (Fig. 13) and spectral distribution of variation was also briefly discussed (Fig. 14).

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