Stan Gibilisco

“Problem 7-4
Can used cooking oil or grease, such as that from a deep-fat fryer or a frying pan, be poured into the fuel tank of a diesel-powered vehicle and consumed as biodiesel? […]

Solution 7-4
Absolutely not! Demised cooking oil or grease must be processed as shown in Figure 7-4 [page 125, a process that involves methyl alcohol and sulfur] before it can be used as biodiesel. This should be obvious in the case of bacon grease, which solidifies near room temperature. But it is true even of fats that remain liquid at relatively low temperatures, such as corn oil, canola oil, or even soybean oil.”
― Stan Gibilisco, Alternative Energy Demystified

“The relation shown in Fig. 1-1 can be modified to make it a function. We must eliminate two of the three pathways from c in the domain. It doesn't matter which two we take out. If we remove the pathways represented by (c,v) and (c,z), we get the function illustrated in Fig. 1-2.”
― Stan Gibilisco, Calculus Know-It-ALL: Beginner to Advanced, and Everything in Between