"I'm sad to say that your dark theory about my profession may be true," I said to Holmes as I lowered my copy of the Times.
My companion looked up from the chemical experiment that he was performing. "That a doctor, when he goes wrong, has the nerve and knowledge to be a top criminal? Tell me of the article you have just read."
"It appears that a doctor poisoned one of his patients, whom he was also courting, with arsenic."
"Most curious. My theory about your profession would in fact argue for his innocence. Has the doctor confessed?"
"No, but it looks as if the authorities have a solid case against him. Let me read you the article.
"Robert Lane, 35, medical
doctor, has been arrested for suspicion of murder by the Metropolitan
Police after the coroner declared that his lover, Patricia Ellison,
age 25, died of arsenic poisoning and the police discovered a
container of arsenic in the doctor's medical bag. Lane met the
girl Ellison three months ago when he treated her for a stomach
ailment. Ellison, the daughter of a rich garment factory owner,
recovered from her malady after two more professional visits by
Lane, but the pair continued to meet on intimate terms. On the
day before her death, a loud quarrel took place and the doctor
was overheard declaring that he would not see her again as long
as she lived. This statement was true, because the pretty young
lady with a pale complexion and rosy cheeks was killed when she
next took the medicine prescribed by Lane. The medicine was evidently
replaced with arsenic by the doctor after the quarrel. The doctor
was a respectable member of the medical community before his scandalous
affair with Ellison. However, recently his ethics have been criticized
for his taking advantage of a vulnerable patient to gain the favour
of the wealthy Miss Ellison over several gentlemen suitors. Lane
has professed his innocence, but has otherwise refused to talk."
I put down the paper and concluded, "Unfortunately for my profession, all the evidence clearly points at Lane as the murderer."
"On the contrary," said my companion, "all the evidence points to his innocence."
"Come now Holmes, how can you possibly say that? The police have a solid case!"
"Circumstantial evidence is subject to interpretation. The police have simply twisted the facts to suit their theories instead of using theories to suit the facts. Why would a doctor, who has the necessary knowledge at his fingertips to select a poison that is not detectable by modern chemistry, foolishly choose arsenic? I can name half a dozen poisons that are easily accessible by a doctor that are a more suitable choice for murder. Why would a murderer replace the medicine that is associated with himself? Morals aside, I refuse to believe that a man capable of becoming a respectable member of the medical community could be so irrational."
"Surely this scandalous affair is evidence of his irrationality."
"If the affair was instigated with monetary incentives in mind, as implied by the article, then this would illustrate a devious nature, and not an irrational one. Why would he kill her when he has nothing to gain by her death at this time? If this was truly an affair of the heart, I can see no motive for the supposedly premeditated act of substituting the medicine with poison. Such an act does not occur impulsively as a result of a quarrel."
"How do you explain the arsenic in the medical bag? While arsenic has some medical uses, it is not used for on-site immediate treatment of patients and therefore not normally found in a medical bag."
"Do you have arsenic in your medical bag?"
"Most certainly not."
"Then perhaps you can humour me and let me test your assertion."
It seemed a strange request, but I had come to expect that from Holmes. I went to my room and retrieved my black bag and handed it to Holmes. He took my bag over to the corner of the room which contains his formidable collection of chemicals and test tubes on top of his acid-stained table and opened it. He took out a bottle of chlorate of potassium from my bag and placed it on the table.
"I will now perform the Reinsch test, one of the standard tests for arsenic, on the contents of your bottle."
He boiled some of the chlorate of potassium in hydrochloric acid. He then dipped some copper foil into the pungent solution, and a reaction occurred. "See Watson, proof that you have arsenic in your medical bag!"
"But that is preposterous, there is something wrong with your test!"
"Actually, the test is quite accurate for many substances, but chlorate of potassium releases the arsenic impurity inside the copper foil, and it is the copper's own arsenic that reacts. If we were to redo the experiment with the Marsh test, we would find that the bottle did not really contain arsenic."
"So you think that the police used the Reinsch test and the doctor did not give her arsenic?"
"I'm almost certain of the first, but not the latter."
"So, you think him guilty of murder after all."
"No, I do not. However, he probably contributed to her accidental death."
"Holmes, stop being so cryptic and explain to me what you think occurred."
"Then I would be as guilty as the police in formulating my theories before I have all the facts." He thought for a moment and continued, "But perhaps I can help you draw your own conclusions. You have already seen how it is possible for a test for arsenic to get a false positive, and you also have heard my doubts about the doctor's method and motives. Could you tell me more about the medical uses of arsenic?"
"Arsenic can be combined with other medicines to treat asthma. It is often used in a variety of health mixtures. For example, liquor arsenicalis can be drunk up to five times a day without ill effect. A sixteenth part of a grain is harmless, but 2 grains is deadly. Small quantities of arsenic can be taken over a long period of time, as has been proven by Hungarian peasants, who have it as part of their regular diet."
My friend inquired, "Yes, but why would somebody who is not suffering from asthma take it?"
"It has been known to improve one's complexion, like a natural cosmetic." I looked at Holmes with sudden comprehension of where he was leading me. Holmes had a twinkle in his eye, and a slight smile began to form on his closed lips. I continued, "In small doses, it causes the skin to look silky and pale, but the cheeks to be rosy. You think that Miss Ellison has been a long-term user of arsenic! Let us look at the article again. Doctor Lane initially treated Miss Ellison for a stomach malady, which would be consistent with a mild overdose of arsenic. But assuming the doctor knew about the arsenic, the treatment would be simple and would not require further visits."
"But what if she refused to stop? After all, she was known for her fine complexion."
"I'd make sure that she took it only in small doses."
"And maybe provide her some arsenic?"
"Arsenic is easily obtained from an apothecary. But if she didn't want anybody to know, it can also be obtained from boiling fly paper or even wall paper."
"Or from a garment factory. Young woman connected with mills or colour works have easy access to arsenic. I ask again; knowing that the young lady is determined to take arsenic, which you stated may be beneficial in small doses, and knowing that she has taken incorrect doses in the past, would you not provide her with some arsenic that contained the correct dosage?" Holmes inquired.
"It is possible. So, you think that the medicine prescribed by Lane was actually arsenic all along. Furthermore, you think that Lane did not have arsenic in his medical bag and therefore the arsenic was not substituted after their argument. It would also help explain why the doctor is not talking, because it could actually serve to incriminate himself. But why would she not take the correct dose?"
"I can think of several explanations. While the substitution of medicine would not be an impulsive act, the consumption of the medicine could be. At the conclusion of the quarrel, the doctor clearly stated that he wanted to end the affair. If we assume that the argument was about this topic, then Miss Ellison was not in favour of the estrangement. After the argument, she may have been distraught and wanted to kill herself. Possibly she thought that more arsenic would make herself more beautiful and attract her lover back again. On the other hand, she may have been trying to make herself sick to force the doctor to see her again."
"It all seems to fit together better than the official explanation. We must test your theory further. What do you plan to do?"
"I think I will suggest to Lastrade that he arrange for the Marsh test to be used on the container from the doctor's bag. Like your bag, I expect the container to actually hold chlorate of potassium. After your recent publication of that case involving Lastrade, he could use a boost."
Two days later, the doctor was quietly released after
tests on the young lady's hair indicated that she had been consuming
arsenic over a long period of time.
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