Curing rate of epoxy resin lining is an important factor in its corrosion resistance. However, no analytical methods have been known to determine practical curing rate of hardened epoxy resin film. The authors investigated the measuring of curing rate of hardened epoxy resin film by solid tablet method in infra-red absorption spectrography and determined the relation between intensity and curing rate, which was represented by linear straight line.
The curing rate was determined on the basis of the following chemical analysis; radical breakage was made on the resin remained or unreacted in the film by hydrochloric acid-dioxane process and the curing rate was calculated by the amount of hydrochloric acid consumed for the ring breakage.

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Vapor deposition of chromium was conducted by using dicumene chromium. Metallic chromium coating having thickness of 80-100μ was obtained on iron or glass specimens by heating the compound at 300-325°C.
The following chemical reaction was observed on the deposited coating.
(C₉H₁₂)₂Cr→300-325°CCr+2C₉H₁₂
1. The cross section of vapor deposited chromium consists of very fine band structure, which cannot be observed on the section of electrodeposited chromium.
2. The surface of the vapor deposited chromium is very smooth and bright. The reflectivity of the surface is 90% on the coating of 80μ thickness.
3. Hardness of the vapor deposited chromium is Hv 1604-1854, which is much higher than that of electrodeposited chromium.
4. Weight, surface roughness, and reflectivity of vapor deposited chromium on glass specimen were measured after dipping it for 24h at room temperature in conc. HCl, H₂SO₄ (1:1) or aqua regia. Their values were not changed as compared with those of before dipping.
Electrodeposited chromium is very easily soluble in conc. HCl or aqua regia, while vapor deposited chromium is insoluble in the above chemicals.

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