Taken from a commercial website (http://www.mullins.cc/history_of_gas_warfare.htm), it gives most if not all the technical names of the chemicals used during the conflict.
Joe
Gas was invented (and very successfully used) as a terror weapon meant to instill confusion and panic among the enemy prior to an offensive. It was a sort of physiological weapon with the non-lethal tearing agents inflicting as much panic as the dreaded mustard gas.

Gas was available in three basic varieties:

Lachrymator (tearing agent)
Much like today's tear gas and mace, this gas caused temporary blindness and greatly inflamed the nose and throat of the victim. A gas mask offered very good protection from this type of gas. xylyl bromide was a popular tearing agent since it was easily brewed.

Asphyxiant
These are the poisonous gases. This class includes chlorine, phosgene and diphosgene. Chlorine inflicts damage by forming hydrochloric acid when coming in contact with moisture such as found in the lungs and eyes. It is lethal at a mix of 1:5000 (gas/air) whereas phosgene is deadly at 1:10,000 (gas/air) - twice as toxic! Diphosgene, first used by the Germans at Verdun on 22-Jun-1916, was deadlier still and could not be effectively filtered by standard issue gas masks.

Blistering Agent
Dichlorethylsulphide: the most dreaded of all chemical weapons in World War I - mustard gas. Unlike the other gases which attack the respiratory system, this gas acts on any exposed, moist skin. This includes, but is not limited to, the eyes, lungs, armpits and groin. A gas mask could offer very little protection. The oily agent would produce large burn-like blisters wherever it came in contact with skin. It also had a nasty way of hanging about in low areas for hours, even days, after being dispersed. A soldier jumping into a shell crater to seek cover could find himself blinded, with skin blistering and lungs bleeding.

List of gases used in World War I

benzyl bromide
German, tearing, first used 1915

bromacetone
Both sides, tearing/fatal in concentration, first used 1916

carbonyl chloride (phosgene)
both sides, asphyxiant, fatal with delayed action, first used 1915

chlorine
both sides, asphyxiant, fatal in concentration, first used in 1915, cylinder release only

chloromethyl chloroformate
both sides, tearing, first used in 1915, artillery shell

chloropircin
both sides, tearing, first used in 1916, artillery shell (green cross I)

cyanogen (cyanide) compounds
allies/Austria, asphyxiant, fatal in concentration, first used in 1916, artillery shell

dichlormethylether
German, tearing, first used 1918, artillery shell

dibrommethylethylketone
German, tearing, fatal in concentration, first used in 1916

dichloroethylsulphide (mustard gas)
both sides, blistering, artillery shell (yellow cross)

diphenylchloroarsine
German, asphyxiant, fatal in concentration, (dust - could not be filtered), first used in 1917, artillery shell (blue cross)

diphenylcyonoarsine
German, more powerful replacement for blue cross, first used in 1918

ethyldichloroarsine
German, less powerful replacement for blue cross, first used in 1918, artillery shell (yellow cross I, green cross III)

ethyl iodoacetate
British, tearing, first used in 1916

monobrommethylethylketone
German, more powerful replacement for bromacetone, first used 1916

trichloromethylchloroformate (diphosgene)
both sides, asphyxiant, fatal with delayed action, first used 1916

xylyl bromide
German, tearing, first used 1915

Norton Tries to Reassure Residents Over Chemical Weapons Cleanup

By Michael E. Ruane
Washington Post Staff Writer
Thursday, August 20, 2009

Del. Eleanor Holmes Norton toured World War I munitions burial sites in Northwest Washington on Wednesday and sought to reassure the public that the Army Corps of Engineers would continue its search for such materials for as long as it takes.

Norton (D-D.C.) was given a status report by the corps, which has been directing the $170 million, 16-year cleanup of the munitions that are buried in scattered sites in the District's Spring Valley neighborhood.

This month, workers were surprised when they found a flask containing residue of the blistering agent mustard buried in the yard of a vacant house in the 4800 block of Glenbrook Road NW. Officials said they had thought cleanup at that site was almost finished.

Work there has been halted but will resume soon, Norton said as she stood across the street Wednesday morning.

Meanwhile, corps officials said they plan to search with metal detectors in the Dalecarlia woods, along Dalecarlia Parkway, in an area that was once a mortar firing range.

Norton said she has asked the corps to reveal "all of the substances" that have been found in the area, something the corps has not publicly done.

American University, in what was then a remote part of Washington, served as an experimental site for chemical warfare during World War I.

"That was then," Norton said. "Our concern now is not to rewrite history but to keep the corps digging until all concerned, including the Congress of the United States, is satisfied that it's all done."

"Our position is that the corps must remain until there is an objective all-clear here," she added. "Nobody need move out of this beautiful neighborhood. It really isn't fair to alarm people. . . . There is no indication that the neighborhood is unsafe."

There are 1,632 suspect properties in the area, she said. Ninety-eight percent of them have been sampled. About 140 have required cleanup of some kind.

Norton said she has been told that the air in the area is safe, and so is the water.

Some residents remain critical of the corps' work. "Give me a backhoe and ground-penetrating radar, and I guarantee I'll find stuff that they missed," said Kent Slowinski, who said he grew up in the neighborhood.

Others said they are satisfied. "I think that the Army corps has done a fairly comprehensive, conscientious job," said Jeff Stern, who has lived around the corner for 20 years. "I'm pretty comfortable that they're going to clean it up, and we're all going to move on."