The experimental study of pitch trouble described in report 7 was followed up by another serieE of experiments using the same apparatus : several sorts of pitch prepared by mixing up two or three different substances in various proportions were used;the changes produced by cooking in the property of resin from the sap and the heart wood of pine (Pinus densiflora) were examined;resin from the cedar (Cryptomeria japonica) was tested as to its bearing on pitch trouble.
10) The wire-attached proportion was 75% or so for a mixture of saturated fatty acid-a substance incapable of causing pitch trouble by itself-and an oil containing an ester of unsaturated fatty acid in large quantity;it was not so large as to cause pitch trouble for a mixture of saturated fatty acid and a substance containing an ester of the acid, as coconut oil, Japanwax or rosin.
11) The wire-attached proportion was generally 70 %-a percentage suggestive of pitch trouble for a mixture of an oil containing saturated fatty acid or its ester and a-pinen, p-cymen, or turpentine oil.
12) Rosin, a-pinen, p-cymen and turpentine oil caused no pitch trouble when used separately, but a mixture of rosin and any of the three cgher substances had 80% of its volume attached to the wire and caused a serious pitch trouble, probably because the essential oil content acted as dissolvent and increased the viscosity of the mixture.
13) A mixture of pitchabietic acid (70%), an oil-type substance and an essential-oil-type substance -a mixture closely similar in composition to pitch-had 85 to 96% of its volume of wire-attached proportion and caused a serious pitch trouble.The use as the main content (70%) of the mixture of rosin or saturated fatty acid, instead of pitchabietic acid, resulted in the production of a pitch trouble no less serious, The wire-attached proportion was reduced when the pitchabietic acid content of the mixture was reduced from 0.2 to 1.0g (11 to 50 %), , It was seen as a result that pitch trouble was severest when the volume of pitchabietic acid constituted the 70 % of that of the whole mixture and the remaining part was a mixture of an oil and resen or an essential oil.
14) Sapwood resin and a mixture of sapwood resin and unsaturated fatty acid caused no notable pitch trouble, but for cooked sapwood resin the wire-attached proportion was 89%, for its mixture with pitchabietic acid or with knot resin 80%, for heartwood resin 88%, -each a percentage suggestive of a serious pitch trouble-for cooked heart wood resin, as for knot resin, it was too small to cause any pitch trouble.
15) The wire-attached proportion was 3 % or less for pitchabietic acid and for resin acid from heart-wood cooked.
16) The wire-attached proportion was small for cryptopimaric acid, resin from a ceder resin and ceder wood resin, 39% or less-a value not suggestive of pitch trouble-for a mixture of any of those substances and pitch, unsaturated fatty acid, or resen, and 60 % for resin from a cooked mixture of pine wood 8 parts and cedar wood 2 parts, so that the cedar wood reduced the severity of pitch trouble.