The physical properties of deposited film in acid copper plating were studied. Effects of addition agents on the mechanical properties of the deposit film were studied, besides, the excess deposit over the Faraday equivalent was measured. As a result it is found that the addition agents can be classified into three groups as follows.
1) Absorption type addition agent:
Greater change of physical properties and more excess deposit over the Faraday equivalent than in the case of plating in the bath without addition agents were observed.
2) With complex salt type addition agent:
The change of physical properties and the excess deposit over the Faraday equivalent were not observed.
3) Intermediate type addition agent:
The effects of the addition agent lay between those of 1) and 2).

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Pin holes of film produced in plating are generally observed by measuring their number and size, but it is very troublesome to do so. Therefore, a new method to measure pin holes, checker board-like sieve method, was introduced. By this method, it is found that the pin holes can be measured more speedly and accurately. By regulating the size of sieve, the errors of this measurements can be decreased.

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Stress of Nickel deposited in bright nickel plating baths was measured with Brenner and Senderoff type stress meter. Result is as follows.
1) The first class brighteners give compressive stress.
2) The second class brighteners give tensile stress.
3) When a little amount of the second class brightener is gradually added to the nickel plating bath with a certain ammount of the first class brighteners, tensile stress is increased. But, on the contrary, when a little amount of the first class brightener is gradually added to the nickel plating bath with a certain ammount of the second class brightener, tensile stress is not decreased more than a certain definite value.
4) Stress of nickel electrodeposited in the bath with acetylen type brightener and in Weisberg bath, differs greatly depending on the air agitation. When the air agitation is applied, stress in the deposit is greater than when it is not applied.
5) With the acetylene type brightener in nickel plating bath, the higher the concentration of Ni⁺⁺, H₃BO₃ and Dk is and the higher the current density is, the more decreases the stress of the nickel deposit. The higher the concentration of Cl^- and the higher the temperature of bath, the more increases the stress.

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Chemical Plating bath is different from electroplating bath, and unstable such as that nickel ion contained in the bath is deposited without catalizer under certain conditions, that pH and temperature of the bath affect quantity and quality of the deposit, that composition of the bath changes successively in the course of plating operation. The authors have been studying the control of the chemical plating bath, and the obtained data for controling the composition as well as variable factors of the chemical plating bath are herewith reported.
Reducing reagent must be added to the chemical plating bath within about one hour before the plating operation, then, pH is adjusted with ammonia water or sulfuric acid solution. Variable factors of chemical plating bath are nickel ion and hypophosphite ion concentration, pH, impurities, etc. Moreover, the temperature at plating operation affects quantity and luster of the deposit.

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Using the same specimens and solutions as described in the previous report, the e.m.f.-versus time (for one week) of mild steel/Al or Al alloy cells in various aqueous solutions at 60°C was investigated.
In hot tap water, every Al or Al Alloy is temporarily nobler (cathodic) than steel at the instance of immersion, but again returns to the basic state (anodic) sooner or later and finally provides sacrificial protection to the steel. But when Al or Al alloy is nobler than the steel temporarily, the steel electrode surface is attacked more or less. In hot distilled water, it may be said that every Al or Al alloy does not become cathodic. In hot sodium chloride solution, every Al or Al alloy provides sacrificial protection to the steel, except in the case of commercial Al (98%) which shows temporary potential reversal in the M/1000 solution. In hot dilute sulphuric acid and aluminum sulphate solutions, even if Al or Al alloy is always anodic to the steel, the steel electrode is generally attacked because the solution temperature is high.
1) M. Tagaya & S Isa, Jour. Metal Finishing Soc. of Japan, 10, 441 (1959)

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