Chlorine

[Under development: 3 June 2005]

I began writing this fragment shortly after the classroom events to which it relates. I wrote it partly to document (as thinly disguised autobiography) my experience of a science classroom, probably in an attempt to bring closure to my experiences. From the perspective of twenty five years later, I feel horrified at many aspects of my classroom management, particularly in my relationships with the pupils I taught. I did gas myself briefly, through incaution, although to only a minor extent. On this occasion, thank goodness, I did not endanger the safety of the pupils.

Present also in the fragment is the same flirting with proximity to death that haunts much of my writing around this period. From the age of about 17 years, I had become gently, morbidly, fascinated with death and dying. One grandmother had already died, and the other was about to die. My parent's marriage was in its death throes, as was my relationship with my mother. I would be going off to university, leaving Chester, my sense of family, and my childhood behind me, most of it totally unprocessed. Whilst I made no identifiably suicidal attempts, I indulged in risky behaviour as an undergraduate that risks horrifying people: pot-holing, parachuting, jumping over cliffs, and drinking entire bottles of spirits. I am reminded of the film 'Flatliners' (only the first ten minutes of which I have watched). My dreams (nightmares) from my mid-teens to mid-twenties were frequently awful.

At least one of my great uncles was gassed at Ypres, and he lived to tell the tale, albeit with bad lungs, until killed in a training accident in 1944. That I should create in the laboratory a poison that injured and killed thousands of fathers, brothers and sons, including relatives of mine, feels to me now as though they belong in the same frame of reference: something about my need to take power and control over a force that could destroy me as it had destroyed others.

During the mainly European war of 1914 to 1918, on occasions when the wind was considered favourable, chlorine gas was dispersed to kill solders. Of the five thousand who died, many were killed before the removal of their bodies from the silent battlefield. Others lingered for a few days, tenuously hanging on to life in a field hospital, before silently passing away.

Chlorine is a silent weapon, deafeningly so when its presence is known. It can be seen, but only in concentration, or at a distance. In the countryside, amongst trees and bushes, it appears as banks, the size of hills, low, rolling, gently swirling: a yellow-green mist. In a gentle breeze, it floats and swirls as if in slow motion. Though green, it is colourless close to. Wisps of its characteristic smell waft past. Is it real? Is it imagination? Here, but not here. It is stronger here, yes, but now it is going. You smell the reminder of bleach and swimming pools and the smell gets stronger until it feels solid and uncertainty is suddenly dispelled.

Chlorine is poisonous. Yes, it's quite poisonous, but not really dangerous when confined to the quantities produced in a laboratory. In fact, it is an interesting gas. Can you smell it? You know you're talking about a gas with chlorine. No mere will 'o the wisp, no mere vapour.

Chlorine is a pale green-yellow gas, soluble in water and denser than air. It is manufactured industrially by passing an electric current through molten sodium chloride - common salt. Its industrial uses are mainly in the manufacture of plastics and insecticides, as well as the more popularly known germ-killing application in swimming pools. In the laboratory, chlorine can be prepared by pouring concentrated hydrochloric acid onto crystals of potassium permanganate. It is instructive to prepare chlorine in the laboratory: physically, so that the pupil enjoys a rare opportunity to witness a gas, most laboratory gases being colourless and relatively inert; chemically, because chlorine is extremely reactive. Of the two reagents, concentrated hydrochloric acid is a vicious colourless liquid which fumes evilly in damp air, like a potion from some Victorian horror story. The grain-like purple crystals of potassium permanganate, staining water as though sambucca nigra, are often employed to make unpleasant chemicals nastier.

Having emphasised the unpleasantness of chlorine's laboratory parents, it would be unfair to continue denigrating this extremely interesting offspring. Treated with respect, chlorine can teach much. Otherwise, like electricity, chlorine teaches respect. Ephemeral to sight, chlorine's presence can be every bit as real as an electric shock. Wafting hither and thither, now stronger, now weaker, chlorine slows time, isolates the individual. A space opens around your head. You're speaking into a vacuum. Words come dribbling from your mouth. Everything becomes an echo.

"Elsie, have you a towel please, to wrap around the gas jars?"

"Wait a minute, I'll get you my old lab-coat."

"Thanks. Joanne, would you get a couple of asbestos mats, please. Guy, tongs. Just one pair. They're in the third drawer down at the back of my lab. Susan, would you go and fetch the rest of the class and bring them in here? Thank you, Elsie. Oh, Jacquie, would you bring those safety screens from over there. No, closer to Mr Manor's bench. Guy, I said one pair of tongs, not a handful. Come on in, and sit yourselves down. There, yes, thank you. In front of the safety screens, Stephen, unless you want to be taken out in little pieces."

"Well you're behind the screen."

"Yes, well I'm being paid. Now then, when we are all quite ready ... You've all ... Will you be polite enough to listen? I hope that you've all written some notes on chlorine, or at worst, you should have read about it. I want to show you now just what kind of gas it is. I have some already prepared in a gas-jar. Three gas jars, to be precise."

"It's just like Blue Peter, this."

"Can you see the faint greenish tinge in there. Look, I'll put some white card behind it. There! Now compare it with this empty gas-jar."

"That's not empty."

"Well, I know it's a bit grubby ..."

"It's full of air."

"True, Stephen, ..."

"See, I was right!"

"... but a least it's not hot air. Point taken? I want you all to think back to your notes. You should remember that chlorine is a very reactive gas, yes? Comparable, in some ways with oxygen. Oxygen, a colourless gas, essential for like, a lifesaver. Oxygen is given to some people in hospital. Melanie, what is the electrical valency of oxygen?"

"Two?"

"Negative two, yes. Janet, what is the electrical valency of chlorine?"

"Two."

"No, Janet, it is negative one. You have heard of chlorine, haven't you?"

"I think so... it's a gas, isn't it?"

"Would you like to tell us the name of its chemical family? Anyone?"

"Is it a halogen?"

"That's right Elizabeth. And can someone tell me how many electrons it gains, loses or shares?"

"It gains one."

"Well done Susan. The reason why I mentioned oxygen is because we always think of burning as something reacting with oxygen. To be more precise, burning is merely a vigorous exothermic reaction. Guy, what does exothermic mean?"

"Don't know."

"Matthew, you're always keen on giving everyone the benefit of your opinion; perhaps you'd like to tell us what exothermic means.... Don't just sit there grinning inanely. Exothermic means it gives out heat. Supposing we were to produce a vigorous exothermic reaction with chlorine instead of oxygen, we could call this burning, then, couldn't we? Let's see some substances burn in chlorine. Lorna, would you light the bunsen burner, please."

"Where's the matches at?"

"Oh! I put them in my pocket. Sorry. Here. It might be useful if you got out your notebooks to record your observations. I'm now cutting off a small piece of sodium. If you look, you can see that the freshly cut surface is a very light shiny, silvery grey. I'll put it onto a deflagrating spoon so that I can heat it just enough to melt it, but not so hot that it starts to burn in air. Elizabeth, could you whip the cover slip off the gas-jar when I say. The sodium's starting to melt."

"Do I get paid danger money, sir?"

"Now! There! Did you see the white flash? What can you see on the insides of the gas-jar?"

"There's a sort of white powder."

"Yes. Who can tell me what the powder is?"

"Joanne? Elizabeth? Sodium burns in chlorine to produce sodium chloride: common salt. It's essential to life. Without it your nerves would go to pieces. Too much of it on your chips, though, and you'll have high blood pressure when middle-aged."

"Are you middle-aged, sir?"

"You'll be lucky to make it that far, Matthew. Had I washed the gas-jar properly beforehand, we could have tasted the salt; but unfortunately we don't know where the jar's been."

The day had been a fine one in the immediate vicinity of Ypres. It was later reported that at about 17:00, men in forward positions heard a slight hissing from the direction of the German trenches. Within fifteen minutes no less than 170 tonnes of chlorine had been released along a front extending about six kilometres. A light wind of five to six kilometres per hour bore the wall-like cloud towards trenches manned by British, Canadian, French and Algerian troops. Distant observers spoke of a low greenish mist 'such as is seen over water meadows on a frosty night'. The deadly gas brought horror and confusion into the ranks of the Allies. Those capable of doing so fled, only to run the risk of being shot by their comrades unaware of the advancing terror. More chlorine was discharged on an adjoining sector of the front on 24 April 1915, two days after the first, this time against Canadian troops.

No-one knew exactly how many people were affected by the gas. The most common figure is that there were fifteen thousand casualties, of whom five thousand died during or soon after the attacks.

"Sodium is a pretty reactive metal. I'm glad you find that amusing Matthew. Personally, I see nothing of great amusement in the fact. Iron is much less reactive. I have a wadge of iron wool which I'm going to heat in the bunsen flame."

"What's iron wool used for?"

"Scrubbing pans and ovens I should imagine."

"But why's it called wool?"

"Because they used to knit chain mail with it."

"It's now getting hot."

"It looks like fireworks."

"Sparklers."

"Janet, would you do the honours. This one should be... DOWN! Good grief! Is everyone all right. It's a miracle the gas-jar didn't shatter."

"What happened?"

"It was ... an extremely vigorous exothermic reaction: a minor explosion. What colour was the smoke that it made?"

"I don't know, sir, I was under the table."

"Me too."

"Was it grey?"

"Well, more a brown, really. Iron three chloride. Chlorine likes iron so much that it puts it into the positive three oxidation state, it takes three electrons from each atom. Formula for iron three chloride?"

Absent-mindedly scraping together with my index finger some light brown dust from the dark brown bench, I knock with the elbow of my white laboratory coat the cover slip from the third gas jar.

"F.E.C.L. three."

"Well done, Lorna. Good example of a redox reaction, that one. That one."

As with other poisonous gases, the effects of chlorine are related to the duration and amount of exposure. Victims suffering a high dose experience a feeling of intense suffocation, fall to the ground, struggle for a few moments, and die. Those exposed to lower doses suffer from a burning throat and feelings of suffocation, and cough repeatedly. Breathing becomes intensely difficult, and death sometimes follows within two days. The main effect of the gas is to cause the secretion of massive quantities of a frothy fluid into the air spaces of the lungs. As fluid builds up, lack of oxygen induces feelings of weakness, fatigue and headache.

"Are you alright, sir? D'you think he's drunk?"

I open my eyes, and the faces of pupils swim into view. A bell rings, and the faces swirl away. I close my eyes.

Doctors at Ypres were able to detect bubbling noises in the chests of victims. The body temperature would tend to fall, and the features become bluish. When slightly tilted in a head downwards position, the patients sometimes produced over a litre of frothy liquid. Gassed individuals surviving for thirty six hours generally developed bronchitis. The fluid coughed up became greenish and purulent; the pulse became weak and rapid, while respiration became shallow and fast. Headache and debility would develop, persisting sometimes for several weeks. Those who lasted out the initial two days usually made some kind of a recovery.

 p.g.h@btinternet.com