The tone in which the question was asked was so emphatic that she looked at him in surprise. 'No,' she answered, 'the writing is quite strange to me.'
'Then,' said he, 'the writer is possibly a stranger.'
She looked at him with a puzzled expression, and I noticed that he was gazing at her with a strange fixity. After a pause he continued:
'We were speaking just now of unusual circumstances. Would not a gift of food from a stranger be an unusual circumstance?'
In an instant his meaning flashed upon me, and upon her too, for she took the box quickly from her brother and her face became deathly pale.
'I think, Percy dear,' she said, 'if you don't mind very much, we won't touch these tonight. Do you mind?'
'Of course I don't,' he replied, 'if you would rather keep 'em till tomorrow.'
Nevertheless the boy looked curiously at his sister, and it was clear to me that he saw that there was 'something in the wind'. But he asked no questions and made no comment, sauntering back to his tower and looking it over critically.
'It's really rime you went to bed, Percy,' Miss Blake said after a pause.
'Is it?' he asked. 'What's the time?'
'It is getting on for ten, and you have to be up at half-past six.'
'It's always "getting on" for ten, you know,' said he. 'The question is, how far has it got? But there! It's no good arguing. I suppose I shall get chucked out if I don't go peaceably.' He offered a friendly hand to me and Thorndyke in succession, and having given his sister a hug and a kiss, took his departure. And again I thought I detected in his manner a perception of something below the surface that accounted for his sudden dismissal.
'I suspect Master Percy smells a fox,' said I, 'but is too polite to mention it.'
'It is very likely,' said Miss Blake. 'He is wonderfully quick and observant, and he is extraordinarily discreet. In most respects he is quite a normal boy, but in others he is more like a man.'
'And a very well-bred man, too,' said I.
'Yes, he is nice boy and the best of brothers. But now, Dr. Thorndyke, about these sweets. Do you really think there is anything wrong with them?'
'I don't say that,' replied Thorndyke, 'but, of course, when you have swallowed one, it is too late to inquire. May I look at that paper?'
Miss Blake took the slip of paper from the box and handed it to him, and once more the lens came into requisition.
'Yes,' he said, after somewhat prolonged examination of the writing, 'this is not reassuring. It is quite clear that this writing was traced over a previous writing in lead pencil. A hard rubber has been used to take out the pencil marks, but the ink has fixed them in several places. If you look at the writing carefully through the lens you can see the fine, dark pencil line forming a sort of core to the broader ink line. And you can also distinguish several minute crumbs of blackened rubber—little black rolls with pointed ends.'
'But why should it have been written first in pencil?' Miss Blake asked.
'For the purpose of disguising the handwriting,' replied Thorndyke. 'It is a common practice. Of course, in the case of a forger copying a signature, its purpose is obvious. He takes a pencil tracing of the original signature, goes over it in ink and rubs out the pencil—if he can. But it is used in producing feigned handwriting as well. It is difficult to write direct with a pen in a hand which is quite different from one's own. But if a preliminary trial sketch is done in pencil, and touched up if necessary, and then traced over deliberately with the pen, the result may be quite unlike one's own handwriting. But, in any case, this underlying pencil writing is manifestly abnormal and therefore suspicious. Shall we see if there is anything unusual in the appearance of the sweets?'
She passed him the box, which he placed on the table under the gaslight and looked over systematically. Then he turned the sweets, one after the other, on their sides, and when they were all in this position, he again looked them over.
'It seems hardly possible,' said I, 'that the woman—if it is she whom you suspect—could have prepared a set of poisoned sweets in such a short time. It was past four o'clock when she came and looked at the plate, and it is not ten yet. There doesn't seem to have been time.'
'There has been about five hours,' said Thorndyke, 'and I see by the postmark on the wrapper that the parcel was posted in this neighbourhood barely two hours ago. That leaves three hours, which would have been sufficient. But she might have had the things prepared in advance, and merely waited for the inquest to get the name and particulars. And the sender may not be this woman at all. And again, there may be no poison in the sweets. We are only taking precautions against a possibility. But looking at these things all together, there seems to me to be a suggestion of their having been patched with liquid chocolate round the sides. If that is so, they will have been cut open horizontally and the halves fitted together again, and the purpose of the patching will have been to hide the join. Here is a very well-marked specimen. I think we will take it as a test case.'
He picked out the sweet, and with his pocket-knife, began very delicately to scrape away the outer coat of chocolate all round the sides, while we drew up our chairs and watched him anxiously. Presently he paused and silently held the sweet towards us, indicating a spot with the point of his knife; and looking at that spot where the outer coating had been scraped away, I could clearly make out an indented line. He then resumed his scraping, following the line, until he had worked round the whole circumference. And now it was quite obvious that the sweet had been divided into an upper and a lower half and the two parts rejoined.
'I am afraid it is a true bill, Thorndyke,' said I.
'I think so,' he agreed, 'but we shall soon see.' He inserted his knife into the encircling crevice, and giving it a gentle turn, raised the top half, which he then lifted off. At once I could see that the exposed surfaces of the white interior of the sweet were coated with a glistening white powder, worked into the soft material of the filling. Thorndyke produced his lens, and through it examined the cut surface for a few moments. Then he passed the half sweet and the lens to me.
'What do you suppose this stuff is, Thorndyke?' I asked, when I had inspected the sweet, and then passed it and the lens to Miss Blake. 'It looks like finely powdered china or white enamel.'
'It looks like—and I have no doubt is—arsenious acid, or white arsenic, as it is commonly called; and I should say there is rather more than two grains in this sweet. It is a heavy substance.'
'Is that a fatal dose?' I asked.
'Yes. And it is extremely unlikely that only one sweet would have been eaten. Two or three would contain a does that would produce death very rapidly.'
We were silent for a few moments. Suddenly Miss Blake burst into tears and buried her face in her hands, sobbing almost hysterically. Thorndyke looked at her with a curious expression, stern and even wrathful, and yet with a certain softness of compassion, but he said nothing. As to me, I was filled with fury against the wretch who had done this unspeakable thing, but, like Thorndyke, I could find no words that were adequate.
Presently Miss Blake recovered her self-possession somewhat, and as she wiped her eyes, she apologised for her outburst.
'Pray forgive me!' she exclaimed. 'But it is horrible—horrible! Just think! But for the infinitely unlikely chance of your coming in tonight Percy would have eaten at least two or three of those sweets. By now he would have been dead, or dying in agony, and I unable to help him! It is a frightful thought. Nobody would have known anything until Mrs. Wingrave came in the morning and found our bodies! And the wretch may try again.'
'That won't matter much,' said Thorndyke. 'You are now on your guard. It will be best to think as little of this episode as you can. It has been a narrow escape, but it is past. You must fix your attention on the future.'
'But what can we do?' she asked despairingly.
'You must walk warily and never for one moment forget this implacable, ruthless enemy. No opportunity must be given. Do not go o
ut after dark without efficient protection, and avoid going abroad alone at any time. You had better not to go to the gate after nightfall, neither you nor Percy. Can you not arrange for some one to answer the bell for you?'
'I could ask Mrs. Wingrave, the sculptor's wife. Their rooms open on the yard. But what could I tell her?'
'You will have to tell her as much as is necessary. And, of course, Percy must be told. It is very unfortunate, but we can take no risks. You must impress upon him that under no circumstances whatever must he eat or drink anything that is given or sent to him by strangers or of which he does not know the antecedents. Does he go to school?'
'Yes. He goes to the Elizabeth Woodville Grammar School, near Regents Park. He usually gets home about five o'clock. Sometimes I go and meet him, but he has some school-fellows who live near here and who generally walk home with him.'
'Then let him come home with them. There is no reason to suppose that he is in any danger apart from you. And let me impress upon you again that Mr. Anstey and I are always at your service. While this danger lasts—I hope it will soon pass—don't scruple to make any use of us that circumstances may require. If you have to go anywhere at night, we can always arrange for you to have an escort. At a pinch, we could secure the help of the police, but we don't want to do that unless we are compelled. And—it seems contradictory advice to give you—but having taken all precautions, try not to think about this incident of tonight, or to dwell on the danger more than is necessary to keep your attention on the alert. And now we must wish you good night, Miss Blake. I will take these sweets with me for more complete examination.'
'I can never thank you enough for all your kindness,' she said, as he wrapped the box in its original paper, 'and I shall have no hesitation in treating you as the good and generous friends that you have proved tonight. I feel that Percy and I are in your hands, and we shouldn't wish to be in better.' She walked out with us to the gate, and at the wicket shook our hands warmly, and indeed with no little emotion. And when we had seen the wicket safely closed on her, and taken a look up and down the street, we turned westward and started on our way home.
11. THE BLUE HAIR
'What are you going to do, Anstey?' Thorndyke asked as we reached the corner of Jacob Street. 'Are you going to Hampstead or are you coming home with me?'
'What are you going to do tonight?' I asked in return.
'I shall make a rough qualitative test of the substance in that sweet,' he replied, 'just to settle definitely whether it is or is not arsenic.'
'Have you any doubt on the subject?' I asked.
'No,' he answered. 'But still it is not a matter of fact until it has been verified by analysis. My own conviction on the subject is only a state of mind, which is not transferable as evidence. A chemical demonstration is a fact which can be deposed to in sworn testimony.'
'Then,' said I, 'I shall come home with you and hear the result of your analysis, although your certainty would be good enough for me.'
We walked down to the bottom of Hampstead Road where we boarded an omnibus bound for Charing Cross. For some time nothing more was said, each of us being immersed in reflection on the events of the evening.
'It is a horrible affair,' I said at length, assuming that we were still thinking on the same subject, 'and a terrible thing to reflect that the world we live in should contain such wretches.'
'It is,' he agreed. 'But the mitigating circumstance is that these wretches are nearly always fools. That is the reassuring element in the present case.'
'In what way reassuring?' I asked.
'I mean,' said he, 'the palpable folly of the whole proceeding. We have here no subtle, wary criminal who works with considered strategy under secure cover, but just the common arsenic fool who delivers himself into your hands by his own stupidity.'
'But what is the evidence of the stupidity?'
'My dear Anstey!' he exclaimed. 'Look at the crudity of method. The discharge, broadcast, of a boxful of poisoned food under manifestly suspicious circumstances, with the poison barely concealed; the faked writing, which a common policeman would have detected, the absence of any plausible origin of the gift, and the nature of the poison itself. That alone is diagnostic. Arsenic is typically a fool's poison. No competent poisoner would dream of using such a material.'
Why not?' I asked.
'Because its properties are exactly the reverse of those which would make a poison safe to use. The fatal dose is relatively large—not less than two grains and for security, considerably more. The effects are extremely variable and uncertain, making necessary the use of really large doses. The material is rather conspicuous, it is only slightly soluble in water and still less so in tea or coffee; it is easily recognised by simple chemical tests, even in the minutest quantities. It is practically indestructible, and its strong preservative effects on the dead body make it easy to demonstrate its presence years after death. A man who poisons a person with arsenic creates a record of the fact which will last, at least, for the term of his own lifetime.'
'That isn't much benefit to the person who has been poisoned,' I remarked.
'No,' he admitted. 'But we are considering the poisoner's point of view. It is not enough for him to succeed in killing his victim. He has to avoid killing himself at the same time. A poisoner sets out to commit a secret murder, and the secrecy is the test of his efficiency. If his methods are easily detectable, and if he leaves a record which stands against him in perpetuity, he is an inefficient poisoner. And that is the case of the arsenic practitioner. He runs a great present risk, since the symptoms of arsenic poisoning are conspicuous and fairly characteristic; and he leaves traces of his crime which nothing but cremation will destroy.'
Our discussion had brought us to our chambers, where Thorndyke proceeded straight up to the laboratory, breaking in upon Polton, who was seated at his bench, putting the finishing touches to the large and elaborate pedometer.
'We need not disturb you, Polton,' said Thorndyke. 'I am just going to make a rough qualitative test for arsenic.'
Polton instantly laid down his watchmaker's glass and unlocked a cupboard on the chemical side of the laboratory. 'You will want a Marsh's apparatus and the materials for Reinsch's test, I suppose, sir?' said he.
'Yes. But we will begin with the liquid tests. I shall want a glass mortar and some hydrochloric acid.'
Polton put the necessary appliances on the bench and added a large bottle labelled 'Distilled Water,' while I seated myself on a stool and watched the analysis with a slightly vague though highly interested recognition of the processes that I had so often expounded to juries. I saw Thorndyke open the box, take from it the two halves of the divided sweet, and drop them into the little glass mortar, and having poured on them some distilled water and a little acid, rub them with the glass pestle until they were reduced to a muddy-looking liquid. This liquid he carefully filtered into a beaker, when it became clear and practically colourless, like water, and this watery-looking fluid formed the material for the succeeding tests.
Of these the first three were performed in test-tubes into each of which a small quantity of the clear solution was poured, and then to each was added a few drops of certain other clear liquids. The result was very striking. In two of the tubes the clear liquid instantly turned to a dense, opaque yellow, somewhat like yolk of egg, while in the third it changed to a bright, opaque emerald green.
'What are those precipitates?' I asked.
'The two yellow ones,' he replied, 'are arsenite of silver and arsenic sulphide. The green one is arsenite of copper. As there is sugar and some other organic matter in this solution, I shall not carry these tests any farther, but they are pretty conclusive. How are you getting on, Polton?'
'I think we are ready, sir,' was the reply; on which I crossed to the bench on which he had been at work. Here on a tripod over a Bunsen gas-burner, was a beaker containing a number of little pieces of copper foil and a clear, watery liquid which was boiling briskly.
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'This is Reinsch's test,' Thorndyke explained. 'You see that this copper-foil remains bright in the dilute acid, showing that both the metal and the acid are free from arsenic. I shall now introduce a few drops of the suspected liquid, and if it contains arsenic the copper-foil will become grey or black according to the amount of arsenic present.' As he spoke, he took the beaker containing the filtered liquid from the mortar and poured about a tablespoonful into that containing the copper-foil. I watched eagerly for the result, and very soon a change began to appear. The ruddy lustre of the copper gradually turned to a steely grey and from that to a glistening black.
'You see,' said Thorndyke, 'that the reaction is very distinct. The quantity of arsenic present is, in an analytical sense, quite large. And now we will try the most definite and conclusive test of all—Marsh's.' He turned to the other apparatus which Polton had made ready, which consisted of a squat bottle with two short necks, through one of which passed a tall glass funnel, and through the other a glass tube fitted with a tap and terminating in a fine jet. The contents of the bottle—lumps of zinc immersed in sulphuric acid—were effervescing briskly, and the tap was turned on to allow the gas to escape through the jet. To the latter Polton now applied a lighted match, and immediately there appeared a little pale violet flame. Picking up a white tile which had been placed in readiness, Thorndyke held it for a moment in the flame and then looked at it.
'You see,' said he, 'that the tile is quite unsoiled. If there had been the smallest trace of arsenic in the bottle, a dark spot would have appeared on the tile. So we may take it that our chemicals are free from arsenic. Now let us try the solution of the sweet.'
He took up the beaker containing the solution of the disintegrated chocolate, and poured very slowly, drop by drop, about a teaspoonful into the funnel of the bottle. Then, after having given it time to mix thoroughly with the other contents, he once more picked up the tile and held it for an instant in the flame. The result was, to me, most striking. In the very moment when the tile touched the flame, there appeared on the white surface a circular spot, black, lustrous, and metallic.
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