Fang Zhouzi’s Discussion on the Criminal History of Thallium, the Deadly Poison of Zhu Lingan.

Recently, Zhu Lingthallium poisoning incidents have been heated up on the Internet. What kind of element is "thallium" and what kind of historical story is there? Fang Zhouzi published an article "The Legend of a Fatal Element" on Hexun.com’s personal blog on May 17th, telling us the criminal history of the deadly poison thallium.

Discovering new chemical elements was once the highest glory that chemists dreamed of. The British were far ahead in the list of new elements. During 1807 ~ 1808, David discovered or first isolated seven elements. But after more than 40 years, this glory was no longer missed by the British. More than a dozen newly discovered elements were discovered by Sweden, Germany, France, Denmark and Russia. The content of new elements in nature is becoming scarcer and scarcer, and it is becoming more and more difficult to find them.

In 1860, German Bunsen and Kirchhoff invented a new method to analyze the composition of matter — — Spectral analysis. The principle of this method is that a substance is heated at high temperature, dissociated into a gaseous state, and emitted light, which is decomposed into a spectrum composed of colored lines through a spectroscope. Different elements form different spectra. If new lines are found in the spectra, it means that new elements are found. In this way, Bunsen and Kirchhoff discovered cesium and rubidium successively.

Photo of Zhu Ling (taken in 1993)

Zhu Ling after illness.

At that time, crookes, an Englishman, turned to science journalism and edited Chemical News after finding nothing new elements. After learning about the discovery of Bunsen and Kirchhoff, crookes was re-inspired to find new elements. In March 1861, when crookes made a spectral analysis of the waste residue from a sulfuric acid plant, he found that a bright green line that had never been seen before flashed and disappeared. He is keenly aware that this may be a new element. Subsequent analysis confirmed this. He named this new element Thallium according to the color of the lines, which means "twig" in Greek and translated into thallium in Chinese. Crookes immediately published his findings, and then tried to separate this new element. However, he had too few raw materials, and only a little thallium was isolated for research in January 1862. He thought thallium was a heavy metal.

克鲁克斯不知道的是，在海峡彼岸，法国人拉米也在做同样的研究，也独立看到了那条亮绿色线条。但是拉米在5月份当地的一次学术会议上公布其发现时，克鲁克斯早已抢先公布了，所以拉米就沿用克鲁克斯的命名，称之为铊。与克鲁克斯不同的是，拉米手上有大量的原料可供分离。2星期后，他用电解法分离获得铊金属锭。

1862年5月1日，克鲁克斯应邀在伦敦世界博览会上展出他的发现，展品中除了一些铊盐，还有一粒粉末，标注“铊，一种新的金属元素”。当年6月，拉米带着铊锭从法国赶来参展。克鲁克斯和拉米碰头后，才知道拉米也独立发现了铊，而且比他更进一步获得了纯化的铊锭。而拉米则认为克鲁克斯展出的那一粒粉末根本就不是金属铊，而是铊的硫化物。两人自此起了争执。博览会组织者的一次失误让这次争执火上浇油。在获奖名单中，拉米作为铊的发现者获得奖牌，却没有克鲁克斯的名字。在克鲁克斯写信抗议后，组织者承认是编辑错误，在获奖者名单第二版中，把克鲁克斯也作为铊的发现者补进去。

Crookes thinks he is the discoverer of thallium, because he first saw the green lines of thallium, determined the elemental properties of thallium, and isolated thallium. Lamy admitted that he saw the green lines of thallium and determined the elemental properties of thallium independently later than crookes, but he first determined that thallium was a metal and really separated thallium for the first time. Lamy’s view is that only by separating the new element can it be truly discovered. Lamy also accused crookes of plagiarizing his viewpoint. Before that, crookes thought thallium was a metalloid, and only after meeting Lamy at the Expo did he know that thallium was a metal. Crookes denied plagiarizing Lamy’s views, because he didn’t know much French and Lamy didn’t know much English. How could he plagiarize when they met?

Crookes made use of his scientific media to publish a series of contributions to support himself. Other British journals have also published articles in support of crookes. British scientists are happy to support him for British honor. After all, this is the first time since David that the British have discovered new elements and compared him with David. Lamy can naturally make his own voice in the French media. Both sides are fighting for their own priority and the honor of the motherland, and they are quarrelling endlessly. Comparatively speaking, the British scientific community needs this priority more and supports crookes more. In June, 1863, nominated by Faraday and others, crookes was elected as a member of the Royal Society of England at an extremely fast speed, and his achievement was simply listed as "the discoverer of thallium". At this point, crookes became famous and no longer argued with Lamy.

Lamy experimented with thallium and found that thallium was very toxic. He once dissolved 5 grams of thallium sulfate in milk and found that it was enough to kill 2 hens, 6 ducks, 2 puppies and a bitch. Crookes doesn’t believe thallium is poisonous. He said that he had done experiments with thallium vapor for a long time and didn’t get sick because of it; He swallowed one or two thallium salts and found nothing wrong.

There is nothing to argue about on this issue. Thallium is toxic and highly toxic. Thallium sulfate is colorless, odorless and highly toxic, so it is very suitable to be used as rodenticide. Mice will not only die if they eat bait mixed with thallium sulfate, but also die if they eat the bodies of poisoned mice. Thallium sulfate has been widely used as a rodenticide in the world since the 1920s. But this rat poison can also kill people. In the early 1950s, thallium sulfate rat poison was even popular in Australia, and many cases occurred. In Sydney alone, hospitals treated 103 cases of thallium poisoning.

Poisoners like to use thallium for poisoning, because thallium is colorless and odorless, requires a small amount (about one gram can kill them), is not easy to be detected, and the symptoms (gastrointestinal reaction, hair loss, peripheral nerve disease, etc.) after poisoning are easily confused with other diseases, and it is difficult to diagnose. Thallium poisoning has therefore become a common theme in detective novels and movies. One of the most famous is pale horse published by agatha christie, a former pharmacist, in 1961. Because of its accurate description of thallium poisoning methods and symptoms, it was criticized as a poisoning textbook. There are indeed some thallium poisoning cases in which the criminals were inspired by reading pale horse. For example, in the thallium poisoning case in Florida in 1988, the police searched the suspect’s room and found a copy of pale horse. In three cases of thallium poisoning in Japan, whether you have read the pale horse or not was investigated as important evidence, especially in the case of the medical department of Tokyo University in 1991, and the witness’s testimony that the suspect had read the book was even regarded as important evidence.

Pale horse also played a positive role. In 1971, about 70 people developed strange diseases in a factory in Bowen, England, and 3 people died. A doctor who read "pale horse" realized that it might be thallium poisoning and contacted the police. It turned out that an employee who poisoned his family at the age of 14 threw thallium into tea for everyone to drink. In 1977, a 19-month-old baby was sent from Qatar to London for rescue because of a strange disease. A nurse who read "pale horse" suspected thallium poisoning. After testing thallium poisoning, she confirmed her suspicion. However, she was not poisoned, but ate rat poison containing thallium sulfate by mistake.

Thallium has its application value in medical treatment, chemical engineering, material engineering and other fields, but its reputation as a poison is so great that people think that it exists as a poison. In fact, due to the progress of diagnosis and medical technology, thallium is no longer a good poison. It usually takes two weeks or more from onset to death after thallium poisoning. If it can be diagnosed and detoxified in time, there will be almost no sequelae. What is needed is that doctors should have enough knowledge and vigilance against thallium poisoning.