I am doing an art project and I need advice on how to make an idea work…
What flammable substance can I use that would burn for about five minutes with a visable flame… I have heard that gas, diesel, and gelatin together might work but I need another opinion… basically i want to put it on the ground in a long ten foot line… light one end and have the flame run slowly, lighting the rest of the “substance” on the ground…
wow, I hope this makes sense. Any help is greatly appreciated as always. 
Sounds like you need a very big sparkler. But messing with fire is dangerous. You should also check with your local fire brigade about any regulations with which you should comply.
I have some misgivings about the mixture you suggest. Gasoline will probably make it propagate too fast for your purposes, and it’s pretty hazardous to work with. Also, bear in mind that the gelatin will become a lot more runny when it gets hot, so your burning line might turn into a burning puddle.
I suggest that you run a few candles through a cheesegrater and mix the grated wax with gravel sized chunks of charcoal - a rough 50-50 mix to start with. Pour the mixture in a line and place a lit firelighter at one end. The wax should melt and absorb into the charcoal, which would act as a wick and let the flame slowly propagate along the line, melting more wax as it goes. You might have to play with the mixture a little to get the propagation reliable. But it shouldn’t make too much smoke, and it should be easier to handle.
Rubber cement is flammable, stays where you put it, and burns with a visible flame. I’m unsure of the propagation speed, but it’s probably worth a try.