The salt content and temperature of brine collected from each steps of dropwise evaporating system were measured. The decrease of temperature was recognized at each step, but the rates of decrease were nearly proportional to the evaporation rate of brine. The salt content of brine increased at each step, but the rates of increase were greater at the steqs especially at the 1st and 5 th, faced to the direction of wind.

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Refining method dy Na₂CO₃ of salt-water NA hich produced in salt-field is investigated. The rapidity of filteration of the precipitate in refining process and refining rate of Mg, Ca under some refining conditions are considered from the point of view about the mechanism of precipitating qrocess of Mg-carbonate.
There are three Wayo, each of which has a different point of evcellence, but the following method is most profitable. As much as concentrated Na₂CO₃ is reacted to salt-water under room temperature, sufficient stirring is continued and after 30-60 minute sthe needle-like crystalline of MgCO₃ 3H₂O is filterated. In this way, the concentration of Mg, Ca in refined salt-water is about 30-40m Mol/L and it can be used to manufacture Na₂SiF₆ from H₂SiF₆ and by means of X-ray diffraction it is found the state of Ca in this precipitate is not CaCO₃

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The water absorption and the plasticiser loss of soft polyvinyl chloride sheet were measured in resting water, 1, 3, 6, and 10% solution of common salt at 50°C. The limiting water absorption and the plasticiser loss decreased against increase of common salt concentration.
From these results, the linear relation was found between logarithms of the limiting water absorption and of the common salt concentration. The plasticiser loss was accelerated by some of the pigments blended in soft polyviny chloride sheet and prevented by the others.

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Nowadays the important subject in the salt making process using the out-vapour system, is the corrosion of steam compressor. Namely several times the rotor blades maked by the 18-8 stainless steel Were broken in the operation by the cause of stress corrosion. We have been studying and testing the stress corrosion condition of the stainless steel from 1951, using the rotating stress corrosion tester. The testing pieces are attached to the rotating circular plate, and tested in the corrosion circumstance as same as the actual one of steam compressor for salt.
By the result of these test, we can see the next fact, the surface corro sion of 18-8 stainless steel is less than 13-cr stainless steel, but the stress corrosion cracking occur to 18-8 steel after about 5,000 hrs. in the ordinary corrosion circumstance, viz. the steam temperature is adout 100 °C, and cl, amount contained in the steam is about 5p.p.m. -10p.p.m., and after about 1,500 hrs. in the severe circumstance, viz. in the case of the small drop of brine is entrained in the steam. These major cause seems to be the unstability of Austenite-system. In the oposite, as regards 13-cr steel such cracking do not occur, but the pitching of surface is apt to arise.

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Thermocompression type and multiple effect evaporators have been developed recently and furthermore flowing down salt field system are applied with a view to multiplication of salt for alimentary use in salt manufacturing industry in Japan. Salt production by heat of hot spring are now put in practise in several volcanic regions in our country. These salt manufacturing apparatus are usually made of cast iron and steel and corrosion of evaporator and piping of conde nsate are soon became a serious problem because of decrease of durability of apparatus and dimi nution of products by inferior salt. Its slitable selection of metal and its protection are indispensable. We measured the corrosion rates about iron and steel in various experimental circumstances which are considered in salt manufacturing and assume the actual corrosion rate of practical apparatus. The results were followed.
(1) Corrosiveness of NaC1 solution and brine about iron and steel decrease with increase of salt concentration and at room temp. these corrosion rate are not particulary so large. Corrosion rate of mild steel in 0.1% NaCI solution at 25°C is adout 16 m. d. d.
(2) There are maximum corrosiveness at 80°C and the corrosion rate of mild steel in boiling sea water was about 60 m. d. d.
(3) Corrosion rates of machined cast iron were rather larger than mild steel in the total immerison tests.
(4) Agitation or aeration of solution accelerate the corrosion rate remarkably.
(5) Repetion of immersion and exposure accelerate the corrosion.
(6) Corrosion rates of steel pipe at Obama. Hot Spring. Nagasaki. Pref. pumping by air lift were about 530-1150 m. d. d.

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Fe and Cu ions interfere the volumetric determination of Mg and Ca by EDTA (Ethylene diamine tetraacetic acid disodium salt). The allowable coexistence limits were shown, the mechanisms of inhibition of these ions discussed and moreover tried the rapid determination of Fe and Cu ions in brine. The results indicated the allowable coexistence limit of Fe was 30 ppm, and that of Cu 0.3 ppm, but addition of 10% KCN solution made it possible to dete mine Mg or Ca even if more than 200 ppm. Cu is present. And it was found that Fe ion was determined as followo within 5% error; Fe ion solution was adjusted to pH 2-3, coloured by salicylic acid and then titrated with EDTA until the solution is decolourized.
Cu was determined with modified method of the determination of Fe within 4% error: that is, the known cuantity of Fe was added to the Cu solution, coloured with salicylic acid, and then titrated with EDTA.

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When vucuum evaporation takes place in salt making from sea water brine, separating sulfates (CaSO₄₄MgSO₄) are expected to play a many troubles.I studied the forms and amounts in each running vucuum pan founding the following effects.
(1)Interference of salt settling in the pan.
(2)Deterioration of qualities of salt.
(3)Foaming of liquid in fan by the dehydiation of sulfate crystal waters.
(4)Hardening of salt in storage by the hydration of sulfate crystal waters.

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We haue many books or references about the colorimetric determinations of cations, but little of anions. Micro rapid determinations of anions are little less important than those of cations.This author wrote this to help the analysts who treat the micro determinations of anions, thinking collectiuely the results obtained by my reserches and home and foreign references.
I'll be uery grateful if you criticize this booklet.

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