In the previous paper, the author described the result of some experiments about the sulphate determination of water, and he found a direct colorimetric method by the yellow colour of chromate was most useful for 20mg. SO4 per litre or more. The nephelometric determination has been studied here, for more minute quantity of sulphate. Reagents: A. 12 gr. NaCl, 2 gr. BaCl2 2H2O. 4gr. gelatin in 100cc. solution. B. 0.6N HCl. Procedure: to 50cc. of water, add 1 cc. of B and 2cc. of A, and mix well. The turbidity due to barium sulphate suspension is compared with that of the standard nephelometricaily. Results: this method is suitable for the sulphate ion from 3mg. to 25mg. per litre.
As an example of application of Takahasi's method of the determination of period and damping ratio of the irregular motion of an oscillating body, we made some investigations on the periodicity of the dates of freezing of Lake Suwa. In the first place the method was applied to each of four sections into which the whole period of records was divided and next to the whole interval. As we can thought that the curve which was obtaind by the method expresses free oscillation of the system, so that we calculated the period and the damping ratio from that curve. Besides this, other methods, such as partial means and the normal statistical method, namely the method of correlation, have also been tried, We obtained, as a conclusion of these analysis, that there exist 3 years and 33 years periodicity in the dates of freezing of Lake Suwa.
A word “Periodicity” is used in various cases and it seems to need some discussions on it. In this paper “Periodieity” was classified into two, namely periodic and cyelie. The former mcans a real periodicity. such as motion of the pendulum, the latter is a periodicity but not exact as former just like motion of the pendulum under the disturbances. Some methods for the search of hidden periodieity and the classification of this two sorts were proposed, and applied to the discovery of few days periodicity in rain, pressure and temperature in Tokyo, and obtained satisfactory results.
Hitherto in the dynamo-theory of the diurnal variation of the ter estrial magnetic field, we have entirely fixed our attention to the atmospheric tides, but our attention must be also extended to oceanic tides. The author calculates the fields produced by the oceanic tides and finds it comparable with the observed lunar diurnal variation when the earth is covered with the sea-water 2km. deep (its conductivity 4×10-11 e. m. u.) above-mentioned idea. At any rate in future we must expect to pay a careful attention to the oceanic tides in discussion of the lunar diurnal variation of the carth's magnetic field.
Applying a differential equation dθ/dt=-γ(θ-T), where Θ denotes the temperature of room, air t time, T open-air _??_emperature, function of t, γ inhe_??_ent constant of room, the author calculated γ of rooms of three different houses at Ootomari in cases when T was nearly constant all night long, viz. independent of t, at cold season, with a view to investigate spontaneous cooling of room.
(1) As a particular case I have considered the thermometric field for the linear variation of the eddy diffusivity, and prepared k0-λ diagram for practical purpose. (2) To determine the monthly values of the eddy diffusivity, I have taken the simplest formula It is important to notice that the result does not hold for phase lag. The values of κ are large and decrease with hei ht in summer, and viceversa in winter.