i. Unused thickener. Any thickener remaining in opened cans should be discarded. Since moisture in the air can quickly ruin its properties, no attempt should be made to save it.
j. Aging and storing. Newly mixed fuel has the appearance of tapioca pudding. ([Fig 27]) It should preferably be stored overnight before use. It may, however, be fired within 1 hour after mixing. To keep fuel in good condition, drums for shipping and storing must be clean, moistureproof, dry, strong, and unrusted, but not galvanized. They must be kept tightly closed and should be laid on their sides so that rain water will not collect around the bungs.
k. Testing fuel. Before use on missions, all fuels should be tested by being fired from a flame thrower. This is advisable because the characteristics of the fuel ingredients often vary.
Fig 27. Contrasting newly mixed thickened fuel (right) with aged fuel (left).
36. PREPARATION OF LIQUID FUELS.
a. Choice of ingredients. Thin fuels are easy to ignite, but they lack range and are largely burned in flight before reaching the target. For this reason, liquid fuels should contain the lowest proportion of gasoline and the highest proportion of heavier oils that permits easy ignition. In hot climates, less gasoline is needed than in cold climates. Exactness of proportion, however, is not of great importance. Suitable blends are as follows:
(1) Equal parts by weight or by volume of gasoline, light fuel oil, and heavy (bunker) fuel oil. The light fuel oil can be either No. 1 fuel oil, No. 2 fuel oil, automotive diesel oil, or kerosene.
(2) One part gasoline to four parts of cleaned crankcase drainings. ([Par 36e]) Unused motor lubricating oil can be employed in place of crankcase drainings, but usually it will be unavailable for flame-thrower use.