Fractionators take a mixed stream of natural gas liquids (the liquid stuff that comes out of the ground along with natural gas) and process it into pure products like ethane, propane and butane.

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On Wednesday afternoon, the proposal to replace the gas station drew mixed reviews.

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In the first round Symyx researchers mixed these solutions with propylene gas to find out which ones catalyzed the most plastic at 167 degrees.

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For global warming, though, gas is a mixed blessing.

ECONOMIST: Natural gas

The arrival of shale gas has received a mixed welcome from environmentalists.

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Mixed signals to a Fed concerned that higher gas prices and food prices will constrain consumer spending.

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Hydraulic fracturing, or fracking, pumps millions of gallons of water mixed with fine sand and chemicals deep into oil and gas wells to crack gas-bearing rock.

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The shale-gas revolution has been, like all revolutions, a mixed blessing.

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Hydraulic fracturing or "fracking" is a process of forcing water mixed with chemicals through deep wells to shatter and crack hard shale rocks to release the gas inside.

BBC: Hydraulic fracturing

Halliburton said that the report "accurately places responsibility on BP as the well owner for its operational decisions, " which included using a heavy fluid designed to keep gas from entering the well, called drilling mud, that was "too light" and probably mixed with the cement at the bottom of the well, and drilling too narrow a well.

WSJ: Final Oil-Spill Report Chastises BP, Others