‘That is why I was so insistent that an emetic had been administered. And at this point I must say that I am indebted to Inspector Green for his suggestion that the insulin Miss Bowker injected just before supper was also useless. I had overlooked that point, but it makes the work of the murderer more complete and sure. For a girl to eat a large meal under the impression that she is protected by insulin when, in fact, her body has no insulin, is itself a danger to health and must have been a contributory factor to the severity of the sickness and the coma which brought on death.’
Hook gritted his teeth at the thought. He threw cigarettes to Green, Brant and Hill. When he had blown out the match he said in a hard voice, ‘Go on.’
Masters did so. ‘So I set out to look for an emetic and a way of administering it. The only emetics I knew were common salt and ipecacuanha. Because to disguise a dose of common salt large enough to produce emesis would be virtually impossible, I discarded it. I thought about ipecac a little more. It appeared that this, too, was unlikely on several counts—difficulty of obtaining it in sufficient strength unobtrusively, its exceedingly bitter taste in strong doses, and so on. But, as I say, I was initially more interested in finding the way in which an emetic could have been administered. So, for the moment, I no longer concerned myself with the substance itself, and concentrated on the means by which it had been given, without her knowledge, to Sally Bowker. I asked myself the question, “What does a cook use for disguising taste in food?” The immediate answer was curry powder which, I have always understood, was originally used to disguise the taste of meat or fish that, before the days of refrigeration, was not always as wholesome as it might have been—particularly in hot countries. Curry, as you know, is made of turmeric and bruised spices. As far as I could tell, no turmeric—ginger—had been used in the preparation of Sally’s last meal. But what about spices? There were no cloves, mace, nutmeg, cinnamon, peppermint … but I continued to go through every one I could think of … lemon, pepper, coriander, aniseed … It was when I came to aniseed that I knew I had found the method. At the Dent house was a bottle of aniseed—in liqueur form. Anisette. The ideal means of disguising an emetic. And Sally had drunk Anisette after dinner on the Saturday night—although she preferred Benedictine—because Anisette was the only liqueur available. Drinking a liqueur once a week at the Dent house was her one regular indulgence. If I possibly could, I had to know whether the fact that only Anisette was available that night was brought about by accident or design. I believe it was by design. The ruse you complained of, sir, was used to get Harry Dent to say that he was surprised that the other liqueurs were finished, because he had, or so he thought, noted only two nights earlier that the bottles were half full.’
Hook grunted what Masters took to be a sound of approbation or forgiveness for his behaviour at the Tontine.
Masters went on: ‘So I came to the conclusion that the reason for there being only the one liqueur was to disguise the administration of an emetic to Miss Bowker. I was, incidentally, careful to inquire whether anybody else present at the supper party had suffered any ill effects. Nobody had.
‘The emetic used was proving a problem. But as you know, sir, through you I approached Heatherington-Blowers and, thereafter, Bruce the bacteriologist. They very kindly agreed to test the floorcloth as no samples of the vomit itself had been available. They did not know what they were looking for, but eventually they found significant traces of zinc sulphate, which is a stomach irritant, and by this means produces emesis. Heatherington-Blowers pointed out that though zinc sulphate is a stomach irritant, there were no lesions on the stomach linings when he carried out the post mortem. This allowed him to state categorically that the zinc had been administered only a short time before the girl was sick. Zinc is eliminated entirely in vomit and that is the reason it had been overlooked in the post-mortem—it was not there itself, nor were any of its effects apparent, on the membranes of the stomach. So I felt safe in assuming Miss Bowker had been given an emetic shortly before her death, disguised in Anisette.
‘Mrs Dent served the three ladies with their liqueurs. It was a habit of hers always to serve Miss Bowker her liqueur under the pretext of making sure that she was given no more than was good for her.’
Hook said, ‘It’s hard to believe. She liked Sally. Everybody did. Even old Harry Dent did—though I suppose he was a bit worried about his son being tied to an invalid all his days.’
‘Quite,’ Masters said. ‘Mr Dent would rather his son’s wife wasn’t diabetic. So would we all. But it doesn’t mean to say we try to kill off diabetics, or even that we don’t like them. I believe Harry Dent became very fond of Sally before she became diabetic, and his affection for her continued. But he had natural qualms about her state of health and the effect it would have on his son’s life. He didn’t want his son tied to an invalid, but as that was what was going to happen, I think he accepted it, and he looked on the girl as his daughter. With great affection.
‘With Mrs Dent it was different.
‘I’d like you to understand, sir, that for the next few moments I am giving you my deductions, based on what I’ve learned from various sources, including yourself. Brian Dent is an only child. The most unfortunate type of only child—the one with the over-possessive mother. He himself admits this. No girl had ever been good enough for Brian—until Sally Bowker came along. Brian says that he dropped Clara Breese in favour of Sally of his own free will. I doubt this. He may have thought he did, but I believe that if Mrs Dent had approved of Clara, she would not have allowed Brian to drop her. Clara is a girl of strong will, with a mind of her own. Not the sort to allow Mrs Dent to have everything all her own way. Additionally, she is a penniless artist: a girl who must work for her living. Not at all a suitable wife for Brian in Cora Dent’s eyes. Sally Bowker was a cheerful, but more pliant child. More likely to fall in with Mrs Dent’s ideas. And in her case, her work was just a pastime. She came from a well-to-do family—father a farmer in a big way and owner of a thriving light-engineering company. Just the girl to make Brian a smart, pretty wife and Mrs Dent a daughter-in-law who wouldn’t be difficult to manage.
‘I don’t say that Brian and Sally were not in love with each other. I think they were, and I think they would have made each other very happy. But I believe the engagement was only allowed to go through because Mrs Dent approved and showed her approval by offering no objections.
‘The wedding was arranged, and then Miss Bowker was diagnosed as diabetic. This, I believe, upset Mrs Dent’s applecart. You, yourself, told me, sir, that the wedding had been postponed. Why, I wonder?’
‘Because Sally was ill, of course.’
‘No, sir. Miss Bowker was no more ill a fortnight ago when she was originally to have been married, than she would have been in September at the revised date. I believe the first date was cancelled at Mrs Dent’s insistence. She hoped there would be no marriage. Miss Bowker had, as Dr Sisson put it, a metabolic defect. Mrs Dent would not want an imperfect wife for her son. She was determined they shouldn’t marry. But apart from the fact that Brian loved the girl and intended to marry her, he was formally engaged to her, and to break the engagement could have meant a breach-of-promise action with undesirable publicity—because the grounds for breaking the engagement would be such as would arouse public sympathy for the diabetic girl.
‘So a new date was fixed by Miss Bowker. There was no reason for further delay. I believe that when she named the day, Miss Bowker signed her own death warrant. Mrs Dent realized that to save her son from what, in her eyes, seemed a calamitous marriage, she would have to get rid of the girl. From that moment on she began to prepare her scheme, so that when the opportunity arose, she would be ready to put it into operation.
‘She was clever. She had shown affection for the girl before diabetes was diagnosed. She had to continue to show the same affection afterwards, in order not to antagonize her son and to put her in a stronger position for cancelling the wedding altogether. If
Brian was to be her unwitting tool in breaking the engagement, he must not suspect hostility on her part, or the ploy might fail. So apparently all were on the best of terms even to the point of Mrs Dent offering the girl a present of five hundred pounds which she, Mrs Dent, never intended should be given or used. Maybe she also thought that this offer would throw people like us off the scent should the girl’s death ever be investigated.’
‘How do you know that?’
‘I don’t know it, but Inspector Green will bear me out when I say she went all artificially coy when the gift was mentioned on Saturday night. “Oh, Brian shouldn’t have told you. It was just a little family secret.” You know the attitude, sir. Sick-making.’
Hook nodded unhappily. ‘You’re a dab hand at drawing conclusions from attitudes that would escape the notice of other people.’
‘I try to be, sir, because it helps. Particularly in cases like this. But to go on: Heatherington-Blowers and Bruce found a significant amount of zinc sulphate in the vomit. Sergeant Hill and Sergeant Brant visited all the local chemists to try to discover if anybody had bought zinc sulphate from them recently. No luck. But zinc sulphate is one of those fairly common chemicals that boys with chemistry sets mess about with. It is an odourless, colourless, efflorescent crystal or a white crystalline powder. Toy shops sell it in little cardboard drums to youngsters for experiments, because it’s not poisonous. So we tried the toy shops. The proprietor of The Model Emporium remembers selling some a week or two ago to a middle-aged woman. Usually, boys buy it. That’s why he can remember this well-dressed woman, with blue-rinsed hair, coming in for it. His description fits Mrs Dent. You will be asked to arrange an identity parade for him to make sure.’
Hook nodded.
‘And also for one of the girl librarians. She remembers a woman coming to the reference department some weeks ago and asking to see the pharmacopoeias. This woman, too, had blue-rinsed hair, and the girl remembers seeing her about the town on various occasions, so identification should not be difficult.’
‘Why should looking at pharmacopoeias be so important?’ Hook asked.
‘Because Mrs Dent, being a dietitian, would know the difficulties of disguising taste. She would know also—none better—the use of aniseed for this purpose. Hence the Anisette. But it would be better still to have an emetic with a less pronounced taste and no smell, if possible, even though it was to be given in Anisette.
‘Martindale—the authority used by most doctors and chemists—lists seven emetics. Zinc sulphate is the last in the list, and according to the doctors I’ve spoken to, the least well known. In fact, some of them had never even heard of it as an emetic and, therefore, I am assuming that it was unknown to Mrs Dent, too, before she visited the library. I think I can satisfy you as to why she chose zinc sulphate. The seven emetics listed are antimony sodium tartrate, apomorphine, mustard flour, copper sulphate, ipecacuanha and other vegetable expectorants, sodium chloride, and finally zinc sulphate. As you know, two of them, mustard flour and sodium chloride—or common salt—are ordinary household condiments. But how would you disguise an emetic dose of ten grammes of mustard in a liqueur, or enough salt to do the trick in so small a drink? Impossible. That leaves five. But two of these, antimony sodium tartrate and apomorphine are injectables. So they were out, too. That leaves three. Our old friend ipecac—as everybody knows—is very bitter, and the amount needed to produce emesis is so large there would be no room left in a liqueur thimble for the Anisette, let alone enough to blanket the taste. Two left. Copper sulphate is blue. Everybody knows that. I think the thought of the colour steered her clear of copper sulphate, but I think it gave her the idea that these chemicals can be bought at places other than chemists’ shops. She was left with zinc sulphate. And here the properties seemed very advantageous to her. An odourless white powder, very soluble in water—less than one part of water is needed to one part of zinc sulphate—with an emetic dose ranging from only six-tenths of a gramme up to two grammes maximum. In other words, an egg-spoonful of the liquid would be certain to do the trick. Admittedly there is an astringent, metallic taste, but not such that Anisette wouldn’t cover it.
‘I’ve already told you how easy zinc sulphate is to get hold of. What about its effects? Vomiting and incessant retching, followed by extreme prostration. Think of what happened to Sally Bowker. Exactly that. And to add to the suitability of zinc sulphate as a poison for a diabetic are these two facts—that it is eliminated from the body in the vomit as I’ve already explained; and that Martindale cites an example of a woman who, after swallowing one ounce of zinc sulphate became semi-comatose with—and note this bit particularly—a marked ketosis. She died despite insulin therapy.’
‘What’s that? Ketosis?’
‘It’s what diabetics get when their insulin is useless or they don’t get enough of it. It’s what brought on Sally Bowker’s coma.’
Hook said bitterly, ‘I see. It was all laid on very nicely for Cora Dent, wasn’t it?’
‘That’s one way of putting it.’ Masters paused for a moment to see if Hook had any further comment to make. As none came, he said, ‘Shall we push on, sir?’
‘Aye. But I’ll order some tea first. I daresay you could do with giving your voice a rest.’
The tea came in. Masters appeared to be in a hurry. Before anybody had finished drinking he started talking again.
‘I’ve told you how I believe Mrs Dent came to choose zinc sulphate as the emetic, and I think you can safely assume that she will be identified as having bought the chemical. Now we must turn to the insulin. You’ve all seen the aluminium carrying-case Miss Bowker used for her injection materials. A metal box with plastic compartments inside. Miss Bowker carried two bottles of insulin on this occasion—one with a single dose, the other full. The single dose she injected before supper, so we cannot state categorically that it was useless, but I believe it was, as Inspector Green suggested, and I hope you will see why I say so in a minute. We know the full bottle was useless. Tests proved it.
‘Dr Sisson said the useless insulin was not toxic. That means that no poison had been added. Why then was it useless? The hint came when Brian Dent said Miss Bowker was careful never to leave her bag in the heat of the sun. Later, I read the instructions for keeping insulin. It must not be stored on a mantelpiece above a fire, in an airing-cupboard or anywhere too warm. An article on the manufacture of insulin says, and I quote: “Heat is enemy to insulin.”
‘Having established that, gentlemen, I had to look round for a source of heat. Quick heat, because Miss Bowker only left her bag in the downstairs cloakroom for the time she was swimming, and nobody could foresee how short a time that might be. In addition, I believe Mrs Dent—though prepared—only took the decision to act on that particular Saturday night at a quarter to seven the same evening. Why I say this will become clear later. But if you accept my word for it, you’ll see that time was short. The meal was to be at seven thirty and Sally Bowker was meticulous in having her injection exactly half an hour before she ate a main meal. So Mrs Dent was pushed for time. At the most she could expect a quarter of an hour in which to work. At the least a minute or two. So, a slow gentle warmth would be no good for her purpose. The downstairs cloakroom is near the kitchen. In the kitchen was Mrs Dent, and Mrs Dent is the proud owner of an infra-red grill—also in the kitchen. I wandered along to the electricity showrooms yesterday afternoon. A model similar to Mrs Dent’s was on display. Its loading is fifteen hundred watts, and it is advertised as being capable of cooking a steak to perfection in sixty seconds. If it will do that, how long will it take to render useless a phial of insulin to which an ordinary warm atmosphere is “enemy”? I suggest that Miss Bowker’s carrying case was put bodily into the grill for a very short time. Thirty seconds, perhaps.’
‘The whole box?’ Green asked.
‘I believe so. Otherwise the labels on the phials would have been singed. Sisson says there was no sign of that, but the plastic inside the box is s
lightly discoloured and misshapen. In my ignorance, when I first noted this, I thought it was staining and fair wear and tear. I was wrong. Insulin does not stain plastic. Another reason why I think the period was short was because the syringe was in a cylinder of industrial spirit. A prolonged period of fierce heat would have caused that to explode. It didn’t do so. But what undoubtedly confirms my belief that the whole box was heated is the state of the reagent strips in their bottle. The impregnated portion of every strip is dark brown. When I first saw them, I naturally thought this was the correct colour. But whilst reading, I came across some information about them. They should be stored—like insulin—in a cool place. The impregnated portion, when in good condition, is white or cream: too much heat sends them brown, and in this state they are useless. I don’t think that Sally Bowker, who was so careful about everything else, would carry useless testing strips. I believe they were submitted to greater than normal heat after she had packed them in her case.
‘A very few seconds under the infra-red grill would render the insulin useless and the box could then be returned to Miss Bowker’s handbag. When she came in a short time later she gave herself the first of the useless injections. Then she ate her meal, with her previous injection still carrying her over. Then she had the liqueur and emetic. Shortly afterwards she began to feel the effects. The meal had been taken at half-past seven. In less than three hours from the start of it, she was at home, feeling sick. Shortly after that she vomited, gave herself the second useless injection and then, I imagine, was seriously sick again and again, unable even to summon help. She made her way to her bed, lay down, prostrate, became comatose very quickly and then, much later, died.’
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