On the hundredth anniversary of the first fatal use of chemical weapons, we look back at the scientists who risked their lives to fight a new enemy

Chemical warfare made its deadly debut a century ago, at a time when science was still in the era of personal experimentation. Scientists routinely used their own bodies as a laboratory; systematic animal experimentation, while growing in use, remained controversial. The urgency in the first weeks and months after the introduction of chemical weapons was such that many scientists repeatedly exposed themselves to extremely dangerous substances, even to the point of unconsciousness and permanent injury; some ultimately gave their lives.

When the German army released 150 tonnes of chlorine gas near Ypres on 22 April 1915, the specialist engineers wore oxygen breathing apparatus, but the infantry were equipped only with simple masks, nicknamed “Riechpäckchen” or “stink pads”. The French soldiers against whom the gas was released had no protection whatsoever, despite a deserter having shown them his mask several days before the attack, and about 1,000 lost their lives.

Soldiers with knowledge of chemistry immediately recognised chlorine gas from the powerful smell which spread for miles around, and knew that simple measures could be taken to protect against it, and that various solutions, including water, would serve to neutralise it, provided a permeable cloth was available. Readily available were sodium bicarbonate, sodium hyposulphate (used for fixing photographs) and even urine.

Two days later, when the Germans released more chlorine gas, some of the Canadian troops on the flank of the gas attack had basic protection, thanks to Sergeant Harry Knobel, whose understanding of chemistry, had led him to arrange for buckets of water to be available for soaking cloths.

Others had protection provided by nuns at a convent close behind the lines, who had sewn tapes to 3,000 strips of lint to be tied over the mouth. Provided the chlorine had become diluted while drifting from the German lines, breathing through a damped cloth could and did make the difference between life of death.

George Pollitt, a chemist working as an intelligence officer at GHQ, drafted the first instructions suggesting wetted cloths while respirators could be prepared in Britain. The foremost expert on gas poisoning, Professor John Scott Haldane, was summoned to the War Office.

Haldane, the physiologist who had discovered the cause of decompression sickness (or “the bends”), was shown a cotton wool pad used to protect against smoke, which had been suggested by Winston Churchill, then First Lord of the Admiralty. Despite Haldane pointing out it would be of no value, the War Office took up Churchill’s idea of using the Daily Mail to appeal to women to make them for the troops. The appeal was published on 28 April and resulted in tens of thousands of masks being made. They were worse than useless: when wet, cotton wool cannot be breathed through.

Haldane managed to prevent the War Office despatching any to France, but many were sent privately and may have cost the lives of soldiers who tried to use them in place of officially-issued pads. Haldane’s own stop-gap proposals, however, which included using loose earth in a handkerchief or a beer bottle with the bottom knocked off, will not have inspired confidence.

Colonel Edward Harrison, inventor of the Small Box Respirator. Photograph: whatsthatpicture

Soon afterwards, a workable design of pad respirator was put into production, designed by Herbert Baker, Professor of Chemistry at Imperial College, and based on a specimen found on a German prisoner. Baker had already been involved with chemical warfare trials at Imperial College before the German chlorine attack. During these trials, a particularly tall War Office representative had been unaffected by a tear gas in the experimentation trench. Baker’s colleague Jocelyn Thorpe, Professor of Organic Chemistry, resorted to a variation of self-experimentation: he gave a small boy a shilling to stand in the trench. The agent was duly adopted and code-named ‘SK’ after South Kensington.

Baker enclosed a wad of cotton waste in a length of black veiling, commonly worn by women in mourning, which could be tied around the mouth. He devised a mixture of sodium hyposulphite, sodium carbonate and glycerine with which to soak it and tested it against chlorine, bromine, sulphur dioxide and nitrous fumes by liberating the gas into a basin and leaning over it wearing the masks.

At the front, a chemistry graduate serving in the trenches, Leslie Barley, was so alarmed at receiving one of the Daily Mail pads that he got permission to develop a workable respirator in a school science laboratory in Armentières. He devised a similar mask to Baker’s and was able to clear a room filled with chorine using a hand operated crop sprayer. In a few days, 80,000 of his masks were made up in villages and convents behind the lines and issued along with crop sprayers.

Barley was soon sent to join a small team of young scientists, all serving in the forces, who had been rushed from the trenches to another school laboratory near GHQ in St. Omer. JBS Haldane, son of Professor Haldane, made light of their constant exposure to chlorine:“some had to go to bed for a few days, and I was very short of breath and incapable of running for a month or so.” Baker implored his former assistant professor at Imperial, Bernard Mouat Jones to “take care of yourself for everybody’s sake”.

One of their number, Cluny MacPherson, a Newfoundland physician, devised a cloth helmet with a rectangular mica window which completely enclosed the head. The cloth was soaked in the neutralising solution and could be put on in seconds. Professor Haldane, however, objected to it on the grounds that the wearer would be asphyxiated by his own exhaled carbon dioxide, a fear that was disproved by the scientists running around the school buildings wearing the helmet.

While this work was going on, the Germans made nine further attacks with chlorine against troops protected by the most basic measures. They captured a disputed hill, causing heavy casualties to the Dorsetshire Regiment, but in other attacks were halted by desperate British troops wearing the rudimentary cloth strips. Some urinated on the cloths, but mostly they used specially prepared solutions.

One month after the first attack, the Germans attempted a massive release of gas on a 4.5 mile front against troops equipped with Baker’s Black Veiling Respirator. The masks only worked for about five minutes before they needed to be re-dipped and carefully squeezed out; officers had to ensure that each man carefully carried out this procedure without succumbing to the clouds of chlorine gas.

The problem facing scientists of the various armies was vast and complex. Chlorine was simple to protect against compared to more lethal gasses, especially phosgene and hydrogen cyanide. A single design of gas mask was needed to protect against these and a host of other agents, be capable of rapid mass production and be simple and easy to put on by a soldier in a state of terror.

The army insisted on persisting with the hood principle, adding more chemicals to the fabric of the helmet. Research was carried out at army medical laboratories at Millbank in London, in which each new chemical solution was tested on rats, pigs and then a human volunteer. The key discoveries were not made at Millbank but by individuals carrying out self-experimentation: Baker working at his home, Bernard Mouat Jones and Professor Stanley Auld, formerly of Reading University, both working separately behind the lines in France. In late 1915 the head of the Millbank research was removed, after testing using rats was found to be faulty, and in 1916 a research establishment was built for both defence and offense at Porton near Salisbury Plain.

The work of co-ordinating the complex design, testing, and production of a successful gas mask is credited to one man, still little-known. Edward Harrison was a painstaking research chemist who before the war had exposed a series of quack remedies for the British Medical Association. Realising the limitations of the fabric hoods, Harrison used an army water bottle to stack layers of different filter materials, dubbed ‘Harrison’s Tower’, but the authorities opposed a bulky and complex mask. However, Harrison’s abilities led to the development of a compact version, the Small Box Respirator, adopted in 1916.

All combatant nations claimed their own gas masks as superior but eventually the consensus was that the British type was the best gas mask of the war. Harrison died in London on 4 November 1918 of influenza, weakened by two and a half years of constant work and the gas inhaled during the early stages. The Pharmaceutical and Chemical Societies both still award prize medals in his memory.

The work in the St Omer school laboratory was put under William Watson, Professor of Physics at Imperial College and author of a series of text books. He presided over a rapidly expanding team of scientists which moved to a purpose built complex of huts close to GHQ and was responsible for analysing German gas shells for every new chemical agent. The urgency of this work continued until the end of the war and Watson himself ventured into no man’s land under shellfire to dig up vitally important unexploded German shells. Even less well-known than Harrison, William Watson died as a result of cumulative gas poisoning in March 1919.

Simon blogs at SimonJonesHistorian.com