Why did scientists want to test the the effects of mustard gas?

Any new scientific innovation needs to be properly tested before it can be used. This is especially true of chemical weapons such as mustard gas. Scientists developing the gas wanted to discover what kind of effect it would have on the human body, whether it would make for an effective weapon of war. At the same time, they wanted to see what measures could be taken to ensure that those using and handling mustard gas would be protected from its damaging effects.
Even so, the demands of war came before the safety of frontline troops. This meant that the scientists were unable to develop effective countermeasures against mustard gas, not least because their main focus was on developing the gas to be used in war. As such, countermeasures proved hopelessly ineffective. Gas masks worn by soldiers proved virtually useless, as mustard gas was absorbed through the skin, causing severe burning and blistering.