Bunker fuel, commonly used in large Diesel engines, generally contains many corrosives (sulphur, heavy asphalten, sediments, etc.). These corrosives, especially those which contain sulphur compounds, are thought to be the main factors related to cylinder wear.
Series of tests were carried on for the purpose of determining the effect of sulphur contents on the corrosion wear, and investigating the protective property of alkaline lubricant against the wear. Sulphur-increasing agents in different degrees were added in fuel, and several kinds of alkaline lubricants were used in a small single cylinder engine. The followings are the results:
(1) Wear of cylinder liner was practically proportional to the sulphur contents of fuel.
Ratio of amounts of wear occurred with FO-A (S content: 1.3%), FO-B (S: 3.1%) and FO-C (S: 4.8%) was 1:2.25:3.07.
(2) Alkaline lubricant seemed to be effective for preventing the wear so far as its basic property is maintained.
The ratio of amount of wear for samples LO-E (Basic No.:5.7KOHmg/g), LO-G (Basic No.:11KOHmg/g) and LO-C (Standard lublicant for control, Basic No.:1.4KOHmg/g) was 66:61:100.

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Corrosion-inhibition effects of several acid amides, i.e. palmitic acid amide (I), N-methyl palmitic acid amide (II) and N-dimethyl palmitic acid amide (II), which show difference in degree of association were studied. C-O stretching frequency in infra-red spectrometory indicated that I is entirely combined with hydrogen bond, II is combined at large with hydrogen bond, and III is not to be combined at all. The results of corrosion tests conducted with filmed mild steel test coupons dipped into 1% carbon tetrachloride solution showed that the effectiveness of thea mides as inhibitors was in order of III>II>I. In 0.1% dioxane solution, however, three amides were not found to be bonded with hydrogen and corrosion-inhibition test conducted with filmed mild steel test coupons in this solution was appeared to be in order of I>II>III. These results indicated that the unshared pair of electrons which required for chemisorption were blocked with the hydrogen bond.
When the effect of the hydrogen bond was removed by lowering the concentration of carbon tetrachloride solution or increasing the adsorption temperature, the inhibition effect was found to be in order of I>II>III. Furthermore same result in the inhibition effect was obtained when applying dispersant to disperse the amides into water and this meant the dispersant was also effective in dissociating the amides.

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The relays for railway signaling systems are abnormally attacked, when they are used under such conditions that electric discharges frequently take place on the surfaces of their contact points. As the corrosion products, silver nitrate (AgNO₃) and basic copper nitrate [3Cu(OH)₂⋅Cu(NO₃)₂] are formed on the surfaces of silver contacts and nickel coated bronze springs respectively. For the identification of these corrosion products, the interference and absorption procedures are found to be suitable.

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