IN a previous communication1 describing results in which specially purified ascaridole2 was used, it was pointed out that the factor used in the B.P. 1953 for the conversion of volume of titrant into a weight of ascaridole was incorrect, e.g., a sample of Oil of Chenopodium containing 54 per cent. wjw of ascaridole gave a result of 65 per cent. w/w by the B.P. method. Furthermore, because the amount of iodine liberated is not directly proportional to the weight of ascaridole, analysis of samples of low grade oils gave proportionately higher errors in the results than those obtained for high grade oils; an invariant factor is therefore inadequate.A quadratic expression was proposed, which, when applied to the observed measurements using the B.P. procedure, gave correct figures for the ascaridole content of the oils provided that the volumes of titrant were within a specified range. Unfortunately, the use of the expression is time-consuming. TABLE I

1 3 4 5 6 7 8 9 10 11 12 This Paper b.pt., O c. 84/3 mm. 96 to 97/8 mm. 80 to 81/4 mm. 85 to 95/2-5 mm. 113 to 1l4/20 mm. l l 5 j l S mm. -75/13 mm. 83 to 84/3 mm. 83/4-5 mm. 115/15 mm., 8415 mm. 3940/0.2 mm. m.pt., c. -n200 C.' * 0.00" Assay (per cent. v/w ascaridole, iodimetric method) 110.8Authors' values of n, !, -recalculated by applying a correction of -04004 per degree rise of temperature (see later) to enable comparison at 20' C. to be made.

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An automatic control unit, activating electrically operated solenoid valves, is used to regulate the flow of “hot” and “cold” water from two thermostated baths to the jacket of a reaction vessel so that the temperature of a liquid sample within the vessel follows a highly reproducible programmed cycle. A comparison is made of the temperature hysteresis between 23–33° during a 16 min cycle, when the flow rates to the vessel are changed and when the valves are operated manually. The adjustment of temperature hysteresis to effect the accelerated storage testing of liquid preparations is described.

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