The interesting history of invisible ink can be dated back over 2,000 years ago starting with the ancient Greeks and Romans. The first known record comes from Pliny the Elder in his book “Natural History” by using the milk of the tithymalus plant to create the invisible ink. These inks have consisted of various ingredients, including urine, vinegar, lemons, diluted blood, and saliva. The intrigue and mystery of these hidden inks still capture our attention today.
Invisible inks were mainly used during wars to conceal messages from foes. The Revolutionary War, which lasted from 1775 to 1783, saw an increase in the use of invisible inks on both the British and American side. Riding on the coattails of the war’s many successful invisible ink concoctions came a clever idea to use the ink as a way of indicating whether the presumed dead were truly dead. The concept seemed almost magical.
By using acetate of lead to create an ink, the phrase “I am really dead” was written on a piece of paper. The paper was then placed under the corpse’s nose. The body’s release of sulfur dioxide, the consequence of putrefaction, would activate the ink. If “I am really dead” appeared on the paper, the corpse was officially decided dead.
False positives were an occasional problem. Dentistry, as it is known today, did not exist. Common problems like tooth decay and tonsillitis would also cause the emission of sulfur dioxide leading the infamous ink to test positively for one’s death. Although invisible ink tests were as fascinating as they were cunning, its unreliability ultimately led to its abandonment for other more dependable means of testing.
Human bodies have fives stages of decomposition: fresh, bloat, active decay, advanced decay, and dry decay. Decomposition is a process that takes place over days to years, depending on the circumstance of one’s death and the conditions the deceased’s body is subjected to. Weather, moisture, temperature, and oxygenation all contribute to how quickly a body decomposes, but all human bodies go through all stages of decomposition.
The body begins the process of breaking down around 4 minutes after death. The initial process of decay is indiscernible to the human eye; the heart has stopped, thusly blood has ceased to flow. Blood is the mechanism by which oxygen is carried to the cells of the body. When death occurs, oxygen ceases to be carried to the cells, and the cells begin to break down. Observations of the corpse a few hours later would allow some indication the person is dead. Rigor mortis, the stiffening of the muscles, can be observed around four hours after death.
Changes in the skin’s appearance are also notable. A pale complexion due to lack of circulation is observable, but even more disturbing are the blisters that appear on both internal organs and the skin’s surface. The blisters were also combined with an eerie sheen across the surface of the skin.
Although the natural process of decay allowed 18th and 19th century doctors and morticians to be fairly certain the bodies they pronounced dead were fit to be buried, doubts lingered still. The doubts led to the creation of The Prix d’Ourches, a macabre contest put forth by the French Academy of Sciences. The Academy announced they would award 20,000 gold francs to whoever invented a foolproof death test. Professor M. Weber, a forensic specialist from Leipzig, Germany, entered the contest with his own testimonial account. Weber had deduced rubbing prickly bushes over certain parts of a corpse’s body would create a parchment like texture. If the texturing was present, the body was sent for burial. Unfortunately, Weber did not win the grand prize. The prize commissioners attempted to replicate Weber’s findings, but found the test unreliable. Weber was awarded 5,000 gold francs and an honorable mention. A deceased body’s complexion will acquire the paper thin sheen Weber observed, and it was likely coincidence his prickly bush experiment was successful.
At this point, knowledge of the circulatory system was well known. Death tests had gone through many iterations of cardiac-related techniques. Doctors knew the chest was not the only source of detecting a still beating heart. A pulse can be palpated at any point a major artery lies, such as the neck, groin, wrist, ankle, or knee. Despite the lack of major arteries, fingertips were prime points of circulation.
A French doctor by the name of Leon Collangues found that when he put the finger of a living human being in his ear, a vibrating pulsation could be heard. This led Collangues to believe this technique could pioneer the murky waters of detecting death. While this was a somewhat legitimate, and arguably far more humane, method of death testing, the technique did not gain much traction within the medical community. Other methods involving the use of the stethoscope were viewed as more reliable, and sticking a corpse’s finger in one’s ear became a small footnote in Victorian history.
Collangues did not stop with death testing. He believed the vibrations caused by the living human body could be counteracted by external vibrating sources to prevent illnesses and diseases. Regrettably, his research on vibratory sciences led virtually nowhere.