Historical Neurology
The quicksilver prize.
Mercury vapor poisoning aboard HMS Triumph and HMS Phipps
Michael J. Doherty, MD
Abstract
In 1810, two British ships, HMS Triumph and HMS Phipps, salvaged a large load of elemental mercury from a wrecked Spanish vessel near Cadiz, Spain. The bladders containing the mercury soon ruptured. The element spread about the ships in liquid and vapor forms. The sailors presented with neurologic compromises: tremor, paralysis, and excessive salivation as well as tooth loss, skin problems, and pulmonary complaints. The events are reviewed in the context of what was known about mercury vapor inhalation.
In the early nineteenth century, elemental mercury was in great demand. Large volumes were used in the purification of gold and silver ores. Additionally, mercury was used in gilding, plating, and mirror making. Mercurial salts were used in hat making and touted as cures for syphilis and dysentery. Consequently, mercury was valuable: In 1810, 1 lb sold for half a US dollar.1 Spain had a virtual monopoly on its trade, supplying large volumes to Europe and North America. Cinnabar (HgS), mined in both Spain and Spanish America, was smelted and refined into quicksilver, which was ultimately stored at and shipped through the port of Cadiz.2
The setting.
In 1810, two ships of the Royal Navy became contaminated with elemental mercury loaded at Cadiz. The crews developed neurologic compromises characteristic of exposure to mercury vapor. Two secondary descriptions of the accident3,4 and one eyewitness account, written 14 years after the event,1 are the principal sources of this report.
No primary sources such as captain's, ship's, or surgeon's logs were studied.
In 1810, Napoleon Bonaparte's armies occupied much of Europe. Britain, Spain, and Portugal formed an alliance against France. A priority for all countries was merchant and naval access to the Mediterranean Sea and the Atlantic. Spain was under incomplete French occupation, and Cadiz, Spain's major mercantile and naval port, remained in Spanish control. Merchant vessels from Europe, the Americas, and the West Indies continued to ship metals, food, and spices to and from Cadiz. The city was an attractive target.
Cadiz, however, was easily defendable. It is built on a rocky knoll at the end of a narrow peninsula that juts far into the Bay of Cadiz. The harbor provided ample room for the merchant fleet as well as Portuguese, Spanish, and British men-of-war, which served their Cadiz garrisons. Landlocked French forces camped along the shores of the bay and besieged the city as best they could.1 French batteries, although unable to bombard the city, peppered ships that strayed within range.1
On March 4, 1810, a hurricane that lasted 4 days struck Cadiz.3 Anchor cables of ships anchored in the Bay of Cadiz snapped or dragged.1,3-5 Four Spanish and 1 Portuguese ship of the line were damaged along with at least 31 merchant vessels. The hurricane's flood surge grounded or stranded many ships on or close to the French- ontrolled shore. Salvage of damaged ships or goods was a high priority for all parties. To prevent their capture by the French, many vessels were intentionally burned.3-5
The prize.
Ships of two British fleets, the Portuguese and Mediterranean, were in Cadiz in March of 1810.1,3-6 One task was to salvage goods from the wrecked ships.1,3-5 A Spanish man-of-war, La Purisima Concepcion, had been blown onto tidal flats of the San Pietro River.1 Within its hold was a large prize of quicksilver originally loaded in South America. 1,4 Although French soldiers could wade to the vessel at low tide, and their cannons were within range of the Spanish ship, they had no boats with which to transfer the mercury.1 During a succession of nights, British marines in longboats removed 130 tons of the element from the stranded vessel, placing it aboard at least two ships, HMS Triumph (figure),
a 74-gun ship of the line, and the schooner HMS Phipps.1,3,4 Elemental mercury was transported in different ways, most commonly in iron bottles or leather bladders.1 The vast majority aboard La Purisima Concepcion was stored in kidskin bladders, two of which were in turn placed in small kegs. Three kegs were then placed in iron-hooped strongboxes.1,3,4 After removal from the Spanish ship, boxes were stored in the bread or spirit rooms of the Triumph and Phipps.4,5 In a 74-gun, third-rate ship of the line such as the Triumph, the bread and spirit rooms were both on the orlop (lowest) deck, at the rear of the vessel, close to the waterline (see the figure). Because the orlop deck had no gun ports and was not as high as other decks—upper and lower decks had 5 ft of headroom—its ventilation was abysmal (see the figure).
The consequences. The Royal Navy's version of subsequent events suggests that heat and water damage likely eroded the leather bags.4 It was not long before "several tons [of mercury] speedily diffused through the ship, mixing with the bread, and more or less with the other provisions." However, an eyewitness account suggests the sailors may have been under the impression that the mercury was "silver ore" with a high street value. Motivated by greed and ignorance, and with no place to hide a strongbox from their superiors, they intentionally ruptured the bladders.1
The enterprising sailors concealed quicksilver wherever they could: "pockets, handkerchiefs, . . . clothes, hammocks, . . . chests and every hole and corner of the ship, . . . every chink and timber." The men were later seen "on the mole of Cadiz, endeavoring to exchange a handful of quicksilver for a drink of grog."1
Members of the crew of the Triumph and Phipps soon presented with copious salivation followed by oral ulcerations, partial paralysis, tremor, pulmonary congestion, bowel complaints, skin excoriations, gum problems, and tooth loss.1,3,4 (The sources examined provided no accounts of behavioral problems.)
Six hundred fifty men were on board the Triumph. Over 200, most of them noncommissioned, became ill, although the Triumph's surgeon and purser were "among the first and most severely affected."4 They bunked beside the mercury stores (see the figure). It is unclear how many men were sick on the Phipps, though officers of that vessel who slept over the bags of mercury were worse afflicted than the noncommissioned men.3
Although sailors were removed from the vessels, they continued to fall ill. The Triumph was ordered to Gibraltar. The ship was to be cleaned, and the men were to be treated at the naval hospital.4 Sailors were treated with "frequent use of small doses of neutral salts and detergents."4 Three men died from pulmonary disease and two from facial gangrene, but most of the hospitalized were later discharged asymptomatic.
Two remained in Gibraltar, suffering from respiratory complaints. Mice, goats, sheep, pigs, poultry, cats, roaches, a dog, and a canary were less fortunate. All reportedly died.3,4 The Triumph was thoroughly and repeatedly cleaned. The hold was emptied, and its contents, including the shingles used for ballast, were replaced. Almost 8,000 lbs of biscuit, stored in bags in the Figure. (A) HMS Triumph by William Latham. The 74- gun ship of the line had two main gun decks. Below the last gun deck was the orlop deck, which typically had a lower height (5 ft) and no ventilation. (Reproduced with permission of the National Maritime Museum, London, UK). (B) Elevation of a typical 74, not to scale. 1 poop deck; 2 quarterdeck; 3 upper deck; 4 gun or lower deck (the majority of enlisted men, marines, and able seamen slept on upper or lower decks); 5 orlop deck; 6 hold. (C) Plan of a typical 74 orlop deck, not to scale. 7 bread room; 8 steward's cabin; 9 purser's cabin; 10 cockpit, spirit locker, and hatch; 11 sail room; 12 carpenter's room; 13 captain's storage; 14 surgeon's cabin. The salvaged mercury was taken to the bread and spirit rooms. After the bags ruptured, elemental mercury presumably flowed through much of the orlop and into the holds andballast below.3,4,6,7
bread room, was condemned, as "quicksilver mixed with it."4 The Phipps was similarly cleaned, although more pragmatically, by boring a hole through the bottom of the hull and letting the mercury flow out.3 The Triumph left Gibraltar with a recovered crew, new ballast, and fresh provisions. Even after its ablution in Gibraltar, the Triumph remained contaminated: A metallic powder was noted to be accumulating, and elemental mercury appeared within the wood and on exposed metals. furthermore, sailors who embarked from Gibraltar in good health later had mercury-induced illness. In June of 1810, 44 men were removed from the Triumph while it was on its way to Plymouth.
A unique treatment. Henry Plowman, the Triumph's surgeon, noted that crew stationed on the lowest decks were most symptomatic, those on the upper decks least. He witnessed new sailors develop mercury poisoning. Plowman deduced that mercurial vapors, not mercury-contaminated food, were responsible.
4 His conclusion may not have been unique. His treatment, however, was. Lower deck gun ports were ordered open, when it was safe to do so; sleeping on the orlop was forbidden; and no men slept in the lower deck if they were at all symptomatic. Windsails were set to channel fresh air into the lower decks day and night.
These measures proved effective. By July, no new cases were recorded.4 Few men, however, remained on the Triumph. According to the eyewitness, a different ship of war towed the poisoned vessel and a skeleton crew back to Britain.1 By 1812, the Triumph was listed as on harbor duty in Plymouth and was without captain.8 Whether mercury contamination ayed a role in the Triumph's decommission is unclear, though the eyewitness relates that the ship was "as I understood, condemned as unfit for service."1
An explanation. Elemental mercury is more dangerous as a vapor than as a liquid. The vapor is colorless, odorless, and neurotoxic. Plowman's conclusion that the vapors were responsible for the metallic tremors and sickness was correct. Although the boiling point of mercury is high (357 °C) and its vapor pressure at room temperature is low, it equilibrates in room air to a concentration 130 times the industrial ceiling concentration of 0.1 mg/m3—the maximum allowable concentration according to present-day occupational standards.9 This may explain why the men who messed and slept in the least ventilated orlop and lower decks were most affected. The eyewitness to the Cadiz poisoning concluded: "Conversing with several officers of the British Navy on the subject, I was induced to believe that the accident proceeded altogether from the ignorance of all those concerned. . . . [T]he whole business was kept as secret as possible by both officers and men, till the great injury was done, in order to prevent the other ships and their crews from participating in the booty."1
Ignorance of the effects of mercury and its vapor, rather than conspiracy, may have been chiefly to blame for the catastrophe. Evolving knowledge. In early nineteenthcentury Europe, mercury vapor was becoming recognized as potentially dangerous. A fire in the cinnabar mines of Idria in 1803 was among the first-described large accidents involving vapor inhalation.10 Burnett, in his delivery to the Royal Society, credits Plowman with deducing the diagnosis and its cause and instituting appropriate therapy without knowing much of mercury vapor poisoning.4 By 1812, more robust descriptions of mercury vapor poisoning among water gilders in Paris helped codify the descriptive diagnosis of "metallic tremor" or "tremblant metallique."10 By the 1880s, a textbook presentation of mercuryvapor poisoning included weakness, particularly in the upper extremities, with intention tremor and loss of fine motor coordination, possibly associated with numbness. If exposure continued, the tremor became coarser, spasmodic, and difficult to extinguish.10
Feeding was impossible, the speech stuttering. Later compromises included lower extremity, truncal, and head spasms and tremor. Dyspnea, headache, memory loss, delirium, and seizure occurred. 10 The differential diagnosis included chorea, St. Vitus dance, and shaking palsy, though combinations of dyspnea, salivation, tooth loss, skin ulcerations, and behavioral changes seen in patients with a common occupation were outstanding features of mercury vapor poisoning. If the worker was removed from exposure, the tremors and illness, even if they had been progressive, were thought to resolve without sequelae.10
A lesson from history. Elemental mercury vapor is difficult to detect. It is hard to see or smell, and its persistent inhalation may be fatal. Buildings, ships, and other places in which mercury was stored or used extensively in past centuries may remain contaminated today. An otherwise healthy person who presents with tremor of subacute onset, excessive salivation, irritability, headache, and breathing difficulty may have vaporous mercury poisoning, acquired in an environment that remains dangerous.
The patient will need treatment, and the environment identification and decontamination.
For years I've read news stories about dental mercury amalgam fillings that failed to ask vital follow up questions for one to form a better understanding of the true risks involved with exposure to mercury fillings. Rarely was a toxicologist, neurologist or bio-chemist interviewed. Instead, the stories would always give dentists such prominence when promoting the safety of a substance of which they knew nothing about, all while never acknowleding the much lower levels of mercury at which our government has removed other products from the market. So now I'm doing what I can to help raise awareness of the many dangerous aspects of dental mercury fillings.
