1. First, before the dissolution, the sample is ground. The sufficient degree of grinding can directly affect the extraction speed of the fat. The grinding can fully dissolve the fat in the organic solvent such as petroleum ether and ether. 2. When the sample is ground, load the sample into the filter paper tube. At this time, the filter paper tube must be tight, and the height of the filter paper tube should not exceed the return bend, otherwise the solvent will not penetrate the sample. 3. When extracting, use ether as a solvent for fat. The boiling point of ether is about 40 °C, so the temperature should not be too much, generally about 70-85 °C. 4. The reagent used in the experiment must be an anhydrous reagent. For example, if diethyl ether is used in the experiment, the ether must be made to dry ether, because if other substances, such as water, are used, the sugar or inorganic in the sample may be used. The matter is extracted and affects the measurement result of fat. Therefore, it is also necessary to ensure that the solvent cups and other items used in the experiment are dry. 5. Connect a calcium chloride drying tube to the upper end of the condenser tube. This will not only prevent moisture from entering the air, but also prevent the ether from volatilizing in the air, thus preventing the laboratory from polluting the tiny ambient air. If you do not have this device, you can also put a dry cotton ball. Generally, the fully automatic or semi-automatic machine has a cover at the top of the condensing tube, which can also protect the experiment well and avoid the effect of solvent evaporation. 6. After thoroughly extracting the fat with a fat meter, the sample and the ether extract can be dried or the solvent cup can be dried. The drying time should not be too long, because some unsaturated fatty acids are easily oxidized during heating to affect the final result of the fat determination. It can be dried at 100-105 ° C for 1.5-3 hours without a vacuum drying oven.