video, there is a lot of white material coming out of the end of the pipe. and that is the gas. in fact, you can see it float upwards in the video. quite a bit more rapidly than the oil does. >> jeff: and then it turns dark. >> right. and that's the oil. toward the end of the video. i based my analysis -- yeah, go ahead. >> well, i mean, as another engineer, you trace a particle, then, and you have software that measures how fast it's going? >> exactly. the name of the technique is called particle image velasymmetry, and basically that means measuring the velocity of the fluid based on a particle's motion. so typically, the way that this would be done in a laboratory setting is you would have -- you would either put small particles into the flow, or you would have some small particles that lap to