Once the fermentation process that creates the methane is finished, the remaining solid matter, or "digestate" is used as an organic fertilizer for crops that will later be used as feedstock for the animals.

CNN: Elephant-poo power electrifies zoo

Which is why scientists have decided to look no farther than the Earth itself for elusive particles which are thought to be as old as the Universe and endowed with the ability to traverse solid matter: neutrinos.

UNESCO: Open Access to Scientific Information

At one fetid pit in a jungle glade, he stepped gingerly onto the surface of the pool, where the solid matter in the produced water had congealed into a tarlike crust that was sturdy enough to support him.

NEWYORKER: Reversal of Fortune

How can we make it so solid that it stays there, no matter who, what administration comes in?

WHITEHOUSE: President Obama Opens Tribal Nations Conference

In any event, Sudan may be losing its lock on diplomacy and the once-solid backing of the Arab countries that matter.

ECONOMIST: Sudan

Stewart, meanwhile, used almost all of his interview time to cross-examine Gore on the matter, pressing him for a solid nine minutes and even picking it up again briefly after a commercial break.

FORBES: See Al Squirm: Gore Faces Tough Questions on Al Jazeera Deal

But that will matter little to Hodgson as he contemplates the solid defending that yielded his side's first clean sheet since August, not to mention the possibility of sealing a top-half finish at Newcastle next weekend.

BBC: Youssouf Mulumbu

Such objections may not matter ultimately in the House, where Democrats have a solid majority.

WSJ: Coming Next: The Act II Blueprint

First introduced by Alan Guth of MIT in 1980 to explain (among other points) why the geometry of the universe appears to be flat and why matter is distributed so evenly throughout space, the theory also offered solid grounds for modeling how galaxies formed as the universe evolved.

FORBES: While Physicists Celebrate Higgs, Cosmologists Fret About The Big Bang Model