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  • The Chemistry of BlacknessBenjamin Rush, Thomas Jefferson, Everard Home, and the Project of Defining Blackness through Chemical Explanations

This article examines the chemistry of race at the turn of the nineteenth century. Physicians, philosophers, and intellectuals from Benjamin Rush to Everard Home defined the skin color of Africans as resulting from the changes of the body's humors (or fluids). Radical physicians like Benjamin Rush believed that he could "cure" African slaves of what he identified as indicative of sickness, their skin color, as they were essentially sick white people in his mind. Overall, the study seeks to explain the medical and chemical understanding of race and the potential for "curing" blackness. Often these cures were linked to balancing and unblocking the fluids. A justification for these ideas comes from cases where people seemed to have spontaneously turned black and experiments where black people were turned white.


chemistry, medicine, slavery, race, humors

In 1876, students in practical chemistry at the University of Virginia under the tutelage of Dr. F. P. Floyd performed experiments with cadaver skin of [End Page 372] an African-American. They framed differences in pigment from changes in the blood and concluded,

It is natural to suppose that the substance which gives the characteristic black colour to the skin of the negro is probably modified blood pigment, as is pretty generally assumed to be the case in reference to the "melanin" of the choroid coat of the eye; but this point does not seem to have been made until now the subject of experiment.1

Floyd and his students were far from the first to analyze racial characteristics in terms of anatomical chemistry. Chemical ideas about skin color had already been formulated and discussed for more than a century, though they came to the forefront of study in the highly racialized times of the late nineteenth century.

During the late eighteenth and early nineteenth centuries, physicians, surgeons, chemists, and philosophers tried to explain the physicality of disease. Some of the writers were pro-slavery ideologues, while others saw intellectual work explaining blackness as potentially liberating. No matter their background, many of these physicians and philosophers framed blackness as a medical illness. They framed blackness to advance other goals: such as being pro-slavery or advocating to end the practice of slavery. Physicians like Benjamin Rush even looked for ways to "treat" the condition. Often, these medical innovations were framed using language and ideas from humoral theory.

Blackness was considered a humoral imbalance, often an imbalance or disease of the bile. Temperamental issues were linked to blackness, as heat has a drastic effect on the body's skin and internal fluids, and surgeons like Everard Home developed experiments to prove it. Chemists wrote of skin changes as related to atmospheric conditions—perhaps different types of air produced the color?—and they tried to determine if different chemicals could remove the color of the skin from the body.

Scholarly conversations defining blackness further strengthened the tentacles of the institution of slavery in what Eugene and Elizabeth-Fox Genovese would call the world the slaveholders made.2 Todd L. Savitt has discussed the racialization of black slave bodies in creating medical knowledge in antebellum Virginia, and Michael Sappol's work regarding the practice of cadaver dissection in relation to the American medicine profession lends itself to a study of cultural change and racism.3 Kipple and [End Page 373] Kipple have discussed the institution of slavery and its effect on the nutrition and health of black slaves.4 The standard for Rush's both progressive and backhand racist attitudes towards African slaves is Donal J. D'Elia's "Dr. Benjamin Rush and the Negro."5

Recently, Peter McCandless wrote of slavery and its relationship to southern diseases and tropical fevers, framing it around the institution of southern slavery.6 Joyce E. Chaplin gave a historical treatment to debates about medicine and the body, framing the discussion around Indians, which can also be found in the work of Winthrop Jordan.7 Roxanne Wheeler pointedly reminded her reader that concepts of race were "elastic" and fluid, going beyond mere complexion.8

Andrew Curran, who focused more on the discussion of intellectual physicians and philosophers defining race, explained that the discussion of race as a concept was tied up in reconciling new ways of knowing in their quest to explain "anthropopoiesis."9 Curran pointed out that the scholarly literature focuses on the construction of differences in regards to framing and furthering the explanation of human bondage and not enough on the scholarly work of the Enlightenment, during which most scholars believed that humanity had a single origin. Curran points to concepts like "white-negroes" that let to intense intellectual debates concerning the construction of difference. Curran also notes the Medical Society of Paris's efforts to research the humors.10 Rhetorically, scholars like Brent Haze pointed to the difficulty of even discussing the concept of race.11

Philosophical discussion regarding race and anatomy often benefited from scientific work during the eighteenth and nineteenth centuries. Rhetoric defined and redefined the emerging science of ethnography. Other scholars, like Cristina Malcolmsom, argued that chemists like Robert Boyle moved science toward racialization by his emphasis on skin color as of interest to experimenters.12 Medical historians have continually reminded readers that racial categories were not completely fixed during the eighteenth century but continued to become more so because of changing society and prejudices produced through the institution of slavery.13

My article examines the chemical analysis, surgical research, humoral medical ideas, and philosophical debates regarding the explanation of skin color through the wider focus of medicalizing skin color difference. In this article I seek to explore the agendas and contextual projects that each physician, philosopher, and surgeon saw as the stakes of their work. [End Page 374]

Physicians' Desires to "Heal"

Benjamin Rush was an American physician, politician, and social reformer during the late eighteenth century. As both a chemist and an abolitionist, Rush was extremely interested in the work of Samuel Smith, a clergyman, college president, and writer about the differences between the races.14 He mostly agreed with Smith's findings, writing,

I admit the Doctor's facts, and reasoning as far as he has extended them, in the fullest manner. I shall only add to them a few observations which are intended to prove that the color and figure of that part of our fellow creatures who are known by the epithet of negroes, are derived from a modification of the disease, which is known by the name of Leprosy.15

Overall, Rush's chemical work fit into his overall goal to end slavery. Roxann Wheeler summarizes Rush's and other projects explaining skin color: "The superficiality of complexion generally assumes the primary position in a list of reasons not to enslave Africans."16

Rush believed that black skin was indicative not just of variation but of disease. Rush implied that heat and diet were the main causes of leprosy in Africa and claimed that heat was the cause of Africans' "bilious fevers" and their "savage manners."17 At the time, physicians had observed leprosy to cause the darkening of the skin. Rush cited an affliction from an account in Arabia called "black albaras," where "the Skin becomes black, thick and greasey.—There are neither pustules, nor turbercles, nor scales, or anything out of the way on the skin."18 Darkening skin was the internalizing of the external symptoms.19

Rush consulted the Bible, specifically the Old Testament and found accounts that leprosy caused a "preternatural whiteness" to victims of the disease.20 He analogized this story to the existence of what he called "albanos."21 Europeans exploring in the New World had regarded albinos as diseased and dangerous, and Rush wondered if "albanos" suffered from leprosy. He stated, "The leprosy sometimes appears with white and black spots blended together in every part of the body. A picture of an African man in Virginia in whom this mixture of white and black had taken place, has been happily preserved by Mr. Peale [Charles Wilson Peale] in his museum."22 [End Page 375]

Rush considered leprosy a constitutional problem. He wrote that the disease caused nerve problems, specifically a "morbid insensibility."23 Leprosy robbed its victims of the ability to feel, and, according to Rush, witnesses had reported this symptom in those of African descent as well.24 Rush quoted a Doctor Moseley in highlighting this difference in capacity to feel pain:

". . . They [Negroes] sleep sound in every disease, nor does any mental disturbance ever keep them awake. They bear surgical operations much better than white people, and what would be a cause of insupportable pain to a white man, a negro would almost disregard. I have amputated the legs of many negroes, who have held the upper part of the limb themselves."25

However, the constitution of Africans caused them to suffer from strong venereal "desires," according to Rush.26 Rush pointed to the "big lip and flat nose" as symptoms of leprosy.27 But he could not explain their "wooly heads" through climate or the other reasons mentioned in the beginning of the article and speculated that it, too, was a symptom of leprosy. Rush noted that such hair texture was often found in those suffering from such afflictions as trichoma and plica polonica, which had been documented as occurring in the "Poles."28

He anticipated criticism to this theory. For example, how did the leprosy that affected Africans continue to persist if the disease ought to have lost its strength in subsequent generations, as it did in all other populations in which it was found?29 Rush was uncertain. It was also well established at the time that leprosy was not an "infectious disorder."30 If it was such a strong and insistent disorder, why didn't people catch leprosy and its resulting dark skin through contact? Rush believed that it potentially could do so, though only in rare cases. He cited the example of a woman living in North Carolina whose features changed when she was living with and married to a "black husband."31

Rush claimed blacks were white people who had their skin darkened because of disease; he insisted the darker skin did not indicate any other sort of poor health. He maintained that " . . . negroes are as healthy, and long lived as the white people. Local skin disease seldom affects the general health of the body, or the duration of human life."32 These ideas fit with those from other physicians from that time who had stated that leprosy did not diminish total lifespan.33 [End Page 376]

Rush was not writing from a completely objective perspective. He was steeped in a culture grappling with whether or not a black man could be free and equal to a white man, and fell on the side of believing that the system of white superiority was inhumane and lacking compassion. He wrote,

. . . That all the claims of superiority of the whites over the blacks, on account of their color, are founded alike in ignorance and inhumanity. If the color of the negroes be the effect of a disease, instead of inviting us to tyrannise over them, it should entitle them to a double portion of our humanity, for disease all over the world has always been the signal for immediate and universal compassion."34

Rush wrote that if some men did have darker skin as the result of disease, ". . . let science and humanity combine their efforts, and endeavour to discover a remedy for it. Nature has lately unfurled a banner upon this subject."35

Rush then recounted instances where black people were cured of their dark skin. The case of Henry Moss, for example, played into Rush's humoral explanation of the question at hand. Moss's skin had been gradually turning from black to a "fleshy white" for five years.36 The wool of his head had "changed into hair."37 Rush explained the changes in terms of fluids. He wrote, "In Henry Moss the color was first discharged from the skin in those places, on which there was most pressure from cloathing [sic], and most attrition from labor, as on the trunk of the body, and on his fingers."38 Rush continued to describe the change in Moss by speaking of the "absorption" of the "colouring matter" in the area of the "rete mucosum."39 He pointed out that

. . . perhaps of the rete mucosum itself, for pressure and friction, it is well known, aid the absorbing action of the lymphatics in every part of the body. It is from the latter cause, that the palms of the hands of negro women who spend their lives at a washing tub, are generally as fair as the palms of the hands in laboring white people.40

In other words, Rush was asserting that darkened skin color was a fluid that could be rubbed or washed off the body or absorbed by it. Medical practice at that time led Rush to prescribe bleeding, then, as a sensible treatment for Africans' pathological dark skin. Rush justified the method, saying, [End Page 377]

Depletion, whether by bleeding, purging, or abstinence has been observed to lessen the black color in negroes. The effects of the above remedies in curing the common leprosy, satisfy me that they might be used with advantage in the state of leprosy which I conceive to exist in the skin of the negroes.41

He believed that the same techniques that were useful in treating leprosy would treat this skin "problem." Rush concluded his article by writing about how much happier blacks would be in having white skin. Healing the condition that caused black skin, he believed, would end arguments for the inferiority of the enslaved. He was certain that the whole human race would be shown to be descended from one single pair of humans, further supporting Christian revelation and inculcating benevolence.42 Rush was captivated by the potential to cease enslavement and inequality, but he was unworried about the racial and paternalistic undertones of his arguments.43 However, Rush's arguments—both chemical and emotional—served to improve the long-term treatment of black individuals in the United States.

The Concept of Race Discussed by Chemists

Theories on explaining blackness through chemistry circulated in intellectual circles on both sides of the Atlantic. W. B. Johnson, in his three-volume Animal Chemistry, recorded strange instances in which the skin of Africans lightened or turned white altogether. William Brooks Johnson was a British physician, chemists, and supporter of the French Revolution. At the time, Johnson explained, chemists and physicians poorly understood the secretions of the body. He attempted to more precisely define bodily phenomena, a "more perfect theory of the laws that govern the vital and mental world."44 Eleven different substances, he wrote, comprised animal life: Fluids, External Parts, Poisons, Concretions, Solids, Oils, Aromatics, Excrements, Hard Parts, Acids, and Colouring Matter.45 Johnson believed that all the parts of all animals, including humans, originated from the secretions of the body. The body was continually forming and renewing itself. Products like urine, sweat, and the faeces removed from "the living machine" were "useless excrement."46 Johnson believed that intense chemical analysis of the eleven parts he qualified "may be a means of casting some light upon the operations and nature of the different functions, and lead to a more exact knowledge of the laws of the animal economy."47 [End Page 378]

Chemistry had already explained the phenomena of respiration, digestion, perspiration, oxygen on the vital forces, and other bodily processes.48 And Johnson admitted that using chemical analysis to understand the "animal substances" was ". . . the least advance[d] of any part of chemistry."49 However, Lavoisier's new French theories of chemistry led the way toward improving these sorts of analysis. Johnson cheerfully explained that the "flow of light which the new French chemical revolution had expanded over a variety of phenomena hitherto obscurely explained, or totally overwhelmed by darkness, enabled to the chemist to pursue a different out from what had been attempted . . . "50

In volume 2 of his History of the Process and Present State of Animal Chemistry, Johnson explored the "Colouring Matter of Animals" and how various parts of animals respond to light. He made several analogies involving Africans and Europeans. For example, he noted that light-colored parts of animals darken when exposed to light. He then went on to say "Thus in Europeans we find the parts of the body exposed to light, darker coloured than those that are concealed."51 In explaining how some animals darken, or produced darker color after birth, Johnson cited the cases of young African children:

Thus we are informed that negroe children when first born are white, and do not become black until after having been a few days exposed to the light, and this blackness is found by observation to be considerably accelerated by early exposure to a strong light.52

Later in this volume, Johnson argued that the effect of light on oxygen might cause it to decompose, which would explain why African children darken from their birth color.53 Pointing to the work of Bancroft and Davy, Johnson hypothesized that something in the African rete mucosum subtracted oxygen. The more oxygen the body had, the whiter the skin seemed. Johnson wrote that the exposure to light in Africa continued to make the mucosum subject to oxygen.54

Thomas Beddoes was a chemist and physician in Britain at the turn of the nineteenth century. While working in Oxford in 1790, Beddoes attempted an experiment on a "distressed negro."55 He attempted to turn the African white with "oxygenated marine acid air."56 The African subjected to the experiment wanted Beddoes to perform this experiment in order to make money on exhibition for his family. [End Page 379]

Beddoes exposed his subject to a large jar full of the oxygenated marine acid air. Beddoes then inserted the African's fingers into the "impregnated water with it at the bottom of the vessel.57" At first, the African felt an itch between his fingers, which gradually changed to ulcerations, and Beddoes began to worry. After twelve minutes of exposure, the African began to feel pain, experienced ulceration, and withdrew his arm. The back of his fingers had turned white, as if lead paint had fallen on his fingers. Some of the subject's hair had also turned white. The pain continued in the African's body the next day, and his hand became inflamed and swollen. Beddoes concluded in the summary of the experiment that, "this deterred him a continuance of the experiment after he was cured of his complaint."58

Chemists speculated that something in the air or in the body caused the skin of Africans to darken. Physicians, chemists, and philosophers during the nineteenth century wanted to understand both the internal and external reasons for the body producing blackness. If physicians, like Benjamin Rush could understand why the body produces black skin, he could reverse the effects. But if intellectuals could understand the reason for black skin he could reinforce racism in the United States.

The Masterclass Sees the Chemistry of Race as Threat

J. H. Guenebault, a French emigre to Charleston, South Carolina, promoted the anthropological work of J. J. Virey, a French physician. Guenebault, a member of the South Carolina Literary and Philosophical Society, translated extracts from the original French from Virey's book Natural History of the Negro Race in order to contemplate the mysteries of creation and also to further the proslavery argument.59

In Guenebault's translation of the book, Virey furthered the argument that differences in bile explain difference in skin color. He explored this within the subsection "Compassion Between the Negro, the White Man, and the Orange Outang" in the section "On the Peculiar Structure of the Negro."40 Virey cites the work of Dr. Mitchel of Virginia, who argued that the intensity of heat on the Africans' outer skin (teguments) explained the "degree of blackness."60 Other French physicians, like P. Barrere, argued that "the extreme heat of the climate thickens and concentrates the bile, which following through the tissues, as in cases of jaundice, renders Southerners dark, tawny and black."61 Philosophers, including Santorini and Springer, are cited because of their findings that the bile in Africans was [End Page 380] black, resulting in Africans having yellowing in their eyes, and having larger "capulese atrabilaires," being more swollen than in people with white skin.62

Virey was skeptical that variations in climate temperature could fully explains variations in skin tone, even though it was one of the more popular theories of his day. Virey reasons that Moors, who lived in Africa, did not become black, nor did the individuals who left Africa or the tropics turn white. People living in India, Virey argued, have some whiteness in their skin, even though they live in a hot climate comparable to part of Africa where individuals have much darker skin. He referenced America as well, and the fact that ". . . the aborigines of that new continent are always copper colored."63 Virey cited the work of the German physician Johann Friedrich Blumenbach and the Scottish intellectual Lord Kames (Henry Home) in arguing that black skin was caused by a humoral imbalance:

Blumenbach attributes the cause of the black tinge in negroes, to their humours, containing a great quantity of carbone, secreted with hydrogene, in the tissues of Malpighi. The oxigene of the air combines with hydrogene, and forms a serosity, which is carried away by perspiration, whilst carone is deposited along under the derma."64

Other scholars argued that there was some fluid in the brain of Africans that caused their dark complexion.65 Anatomists like Malpighi argued that the " . . . this dark color of the African lies in the mucous and reticular tissue."66

However, like W. B. Johnson did, Virey noted adults with very dark skin are " . . . of a yellowish shade . . . " at birth.67 He went on to argue that because the individuals' color darkened with age, it must hold true that the darker a black individual became, the healthier he or she was. In fact, he noted that white men, too, become paler when they are sick or "disposed."68 The African turning a "brown or chestnut color" shows weakening.

To put this in a humoral perspective, the seasons themselves affect the humors, which in excess or deficit, causes changes in skin color. Summer causes "an excess of bilious humors." The temperature acts on temperament, an idea from humoral theory that linked acrimony in the humors to moods. Virey boldly asserts that bile and blood caused blackness:

The bilious temperament prevails among nations of warm and dry countries; wherefore, Moors, Abyssians, Gallas, Giagas, the inhabitants of Barbary are haughterly irascible, active, ferocious, implacable [End Page 381] revengeful. Although the negro species differs from ours, and their constitution is lymphatic, they are not the less affected by the influence of the climate. Their biliary and hepatic systems are exceedingly developed. The exaluation of the bilious humour is chiefly the cause of their disagreeable odor, and is carried over the whole body.69

However, in the "negro species," the "lymphatic constitution prevails over the bilious."70 Virey argued that the phlegm exists around the outside of the body and the bilious protects the internal part of the body. According to Virey, God made Africans in this unique way to protect them in their hotter climates: "The former [lymphatic] is placed at the exterior of the body to prevent in the interior those great commotions, which would destroy it by their excess."71

Virey also hypothesized that the type of food consumed by a population affected the humors, saying, "All the aliments which compose their food are changed into a brownish chyle, which is whitish in the white man."72 Even the lice that attacked Africans were larger and blacker than those attacking the whites. Virey concluded that it is not accurate to only consider temperature as the reason for black skin; the other parts of the body, even all the humours, are important to explain variations in skin color.73

Race and the Weather: Atmosphere, Albinism, and Black Matter

Thomas Jefferson wrote about the differences between African slaves and white Americans in his 1781 and 1782 publication Notes on the State of Virginia. In his publication, Jefferson argued that "natural distinctions" between Africans and whites come from humoral differences:

The first difference which strikes us is that of colour. Whether the black of the negro resides in the reticular membrane between the skin and scarf-skin, or in the scarf-skin itself; whether it proceeds from the colour of the blood, the colour of the bile, or from that of some other secretion, the difference is fixed in nature, and is as real as if its seat and cause were better known to us. And is this difference of no importance?74

Jefferson, like many other thinkers across the late eighteenth and early nineteenth centuries, cited the bile as causing the black color of the [End Page 382] African's skin. By comparing the races in regards to beauty, Jefferson further framed physical differences in terms of the fluids of the body. He wrote,

They secrete less by the kidneys, and more by the glands of the skin, which gives them a very strong and disagreeable odour. This greater degree of transpiration renders them more tolerant of heat, and less so of cold, than the whites. Perhaps too a difference of structure in the pulmonary apparatus, which a late ingenious experimentalist has discovered to be the principal regulator of animal heat, may have disabled them from extricating, in the act of inspiration, so much of that fluid from the outer air, or obliged them in expiration, to part with more of it.75

Jefferson thought that something in the air affected the physical differences in question.

Felix Pascalis, a French physician who travelled to Philadelphia, was an active chemical investigator. Like other physicians of the time, he believed that chemistry and issues regarding the balance of the fluids of the body caused the dark skin color of Africans. In an 1818 Pascalis article, "Desultory Remarks on the Cause and Nature of the Black Colour in the Human Species; Occasioned by the Case of a White Woman Suddenly Turned Black" in Medical Repository of Original Essays and Intelligence,76 he identified himself with the Paris Medical Society and Faculty of Medicine

Pascalis presented the case of Mary Gaillard, a seventy-year-old woman from Peist, who turned black for a brief time. She had previously been free of diseases, but she fell into poverty, homelessness, and begging. Her daughter had to care for her children while she was at work, and the children became sick. The daughter blamed the mother for their illnesses and accused her of giving them syphilis, all of which led the mother to a deep grief. The daughter threw herself out of a window with her two children in her arms and died. Mary Gillard then turned black from her head to her feet.77

Gillard arrived at the infirmary of La Salpêtrière on 28 October 1817, but the doctors could not find any appearance of disease. The black color of Gillard's skin varied, being less intense on her hands, face, groin, and feet; she was a darker black on her abdomen and arms. Her legs retained their white color. [End Page 383]

Pascalis also noted that the patient was in an intense state of suffering.78 The patient experienced a "blistering plaster" which caused "a large venesection."79 A fluid appeared out of the venesection, and "the cuticle, and the cellular tissue were all blackish, as it happens on the skin of the negroes."80 Pascalis went on to describe the "incisions" that were performed on the patient's skin, which produced "rete mucosum which constituted the black color."81 Mary Gillard soon died, and upon autopsy there were no "material alterations," except for what was presumed to have ended her life ". . . a considerable effusion of bilious and purulent matter."82 In his remarks on the case, Pascalis pointed to the older authority Van Swieten, who had also written about a woman who turned black for one year. Pascalis wrote that "the secretion of black matter exists in the white race, and can be proved by numerous facts in the heathy as well as in the morbid condition of the same."83 A white body, he theorized, had this black matter within it at birth. Pascalis calls this matter "meconium."84

According to Pascalis, Black matter was the root of disease. He found this black matter in the subject's retina and hair. He claimed that the matter could be "pressed out" into white linen. The black matter also appeared in the other parts of the body, such as the grandulae renales and bronchiales.85 Cathartics, specifically very strong ones, could remove the matter from the stomach and intestines through "intestinal secretions."86 Pascalis pointed to it causing most bowel complaints. Black matter might have been at the root of yellow fever as well, he thought, as he wrote:

Medical practitioners have sometimes supposed that certain medicines, especially calomel could effect a change of colour in the alvine secretions, and of bile. But in the yellow fever this secretion becomes fatal, and is the most universal and dreaded symptom, for it is produced by it in such a quantity as to astonish, and to bespeak the dissolution of the whole blood.87

The black matter might have also been related to "pulmonary disease or consumption, forming tubercles in the substances of the lungs, that are black and carbonaceous."88 Perhaps Pascalis is arguing that black bile literally causes blackness. Curran found that French scholars were looking to changes in the bile causing blackness, perhaps being found in the skin.89 Perhaps Pascalis, as a chemist, was trying to define a chemically sophisticated definition of blackness. [End Page 384]

Pascalis considered the black matter to be, a " . . . natural secretion of the blood, more or less necessary for certain purposes."90 According to Pascalis, black matter was more abundant in the "African race than in the white race" due to the high levels of carbon in white blood. Africans, he wrote, also absorbed carbon better in response to hot climates.91 Though the amount of carbon he found in the blood was nearly equal in both races, respiration was more difficult in the "burning" or "torpid" climate of Africa. The excess carbon was therefore "deposited" on the skin of Africans. Moreover, through "violent causes," the black matter could have more or less of an effect on the body, " . . . as in the case of the unfortunate Mary Gaillard, and others of the same nature, whose lungs have been by some cause prevented from secreting the carbon of the venous blood."92

Experimentation: The Effects of Heat and Light on Skin

Everard Home was a surgeon and president of the Royal College of Surgeons. In 1820, he read to the Royal Society of London a paper titled "On the Black Rete Mucosum of the Negro, Being a Defence against the Scorching Effect of the Sun's Rays."93 Home wanted to explain the sun's effect on the skin. The subject was of high interest to Home and to his peers: "To ascertain the use of the black colour of the rete mucosum in the Negro, has occupied the attention of many physiologists; and I confess that this subject formed the first investigation in which I ever engaged." In his quest for understanding, Home developed several tests to measure and determine the sun's effect on skin tone and heat absorption. Home found that black-colored substances absorb heat and then increase that heat by several degrees, calling into question many theories of the day.

Early in his career, Home served as a surgeon on a ship crossing the tropics around the West Indies in 1781. Home became tired and decided to lie down for a nap on the ship's deck. He was dressed only in a thin shirt and pants. After an hour and a half, Home awakened and found his body to be noticeably irritated. Though it looked like sunburn, he attributed it to insect bites. Years later, Home read a work by Humphrey Davy that revived his curiosity.

Davy was recounting a story about fish. Davy had observed that a school of silver fish experienced very hot summer sun rays after the trees shading a certain pond had been cut down. The sun scorched the backs of the fish, causing burning all over the scales of the fish. Davy wanted to dissect one [End Page 385] of these fish after it had passed away but did not have the opportunity to do this.

Home theorized that what caused dark areas on the surface of the body—human or fish—was a combination of light and heat that provided the scorching effect. Home tested this theory through several experiments. He tested the sun's effect on himself, with a gloved hand and uncovered hand.94

In this particular experiment, Home held a thermometer in an uncovered hand and exposed it to the sun while keeping a thermometer on an adjacent table to compare atmospheric temperature to the heat he was experiencing. Usually beginning as a blister on the exposed hand, eventually a "coaguable lympth" was produced. Home complained of the pain and noted that the damage was visible with the eye. He then exposed his eyelid, face, and back of his hand to very hot water (about 120 degrees.)95 He produced similarly painful results.

Next, Home performed an experiment with one hand covered with a black cloth while the other hand was uncovered. He measured the temperature of each hand with a thermometer. Over the course of these trials, Home found that the hand underneath the dark cloth measured significantly warmer. However, he found that the sun scorched the areas where the body was exposed.

As a comparison, Home tested the hand of an unnamed African subject. He exposed the African's hand to the sun in the same way he had his own. There was no damage to the African's skin. On 7 September 1820, Home tested his hands once more, in order to probe the effects of the sun on the skin, even a unique event like an eclipse.96 He channelled the light from the eclipse through a double lens half in focus three times during the eclipse. Home found that although he could concentrate the rays from the eclipse such that they did not initially cause him pain, when he had the thermometer raised in the other two periods during the eclipse, the pain in his hands increased, and causing visible injury. When Home continued the experiments, he substituted the black cloth for a white kerseymere, finding that the lighter colored cloth produced visible skin damage in cooler temperatures.

Home was able to conclude that "From these experiments, it is evident that the power of the sun's rays to scorch the skin of animals is destroyed when applied to a black surface, although the absolute heat, in consequence of the absorption of the rays, is greater."97 Extending this to a person with darker skin, Home stated that "providence" had given him this "defence of his skin, while living with the tropics."98 [End Page 386]

From his experiments, Home determines that heat changes the skin to become darker. Much like other animals, their bodies can change color. To the nineteenth century mind, it was perfectly reasonable for people's skin to change colors because of external forces affecting the internal processes of the body.


In white supremacist societies, like the United States and the United Kingdom, blackness was framed as a disease. Physicians, surgeons, chemists, and philosophers framed the disease of blackness to suit their own needs. These needs included furthering a pro-slavery agenda, or attempting to dismantle the intellectual ideas that were appropriated to support slavery. Some radical physicians like Benjamin Rush wanted to use medicine to disprove the idea of black physician inferiority to whites and its weight as a justification for slavery. Chemists interested in expanding the analytical paradigm of Antoine Lavoisier framed the explanation of blackness in regards to its chemical origins in the body. Blackness was a fluid imbalance that chemists thought that they could change and manipulate. Some medico-chemists thought that blackness was literally a fluid state, in which people could change their color.

Chemists like the Thomas Beddoes and Felix Pascalis, whose case studies were mentioned above, believed that they had the power to change people's skin color, even into the late nineteenth century. French philosophers also sought to join discussions about defining blackness as a problem related to the international fluids of the body. It was unclear if climate or atmosphere played a role causing Africans to produce black skin. British surgeons sought to take existing chemical ideas about blackness and put them into experiments, determining how the sun effected the internal fluids of the body. Chemists during the eighteenth and the nineteenth century struggled to define the pathological nature of blackness. [End Page 387]

Edward Allen Driggers
Tennessee Technological University
Edward Allen Driggers

edward allen driggers is an assistant professor of history at Tennessee Technological University in Cookeville. He is broadly interested in the history of medicine and chemistry. He is working on book project about the history of urinary stones in the early nineteenth century.


. I would like to extend a special thanks to Beth Lander, Robert Hicks, Chrissie Perella, Caitlin Angelone at the Mutter Medical Museum and Historical Library. His archival work was supported by a Francis Clark Wood Institute travel grant. I would like to dedicate this article to the memory of Ann Johnson. I also want to thank Dr. Tim Minella and Dr. David Dangerfield for thoughtful comments. I would also like to thank my fine colleagues at the department of History at Tennessee Technological University. Finally, I would like to thank Laura Elizabeth Smith for her love and support.

1. J. W. Mallet, "Notes of Work by Students of Practical Chemistry in the Laboratory of the University of Virginia No. V.," Chemical News, October 27, 1876, 147–69, 190–91; article about Negro skin is on pages 179–80. This particular quote comes from 180.

2. Eugene Genovese and Elizabeth Fox-Genovese, The World the Slaveholders Made (New York: Pantheon Books, 1969); and The Mind of the Master Class: History and Faither in the Souther Slaveholders' Worldview (New York: Cambridge University Press, 2005).

3. Todd L. Savitt, Medicine and Slavery: The Disease and Health Care of Blacks in Antebellum Virginia (Urbana: University of Illinois Press, 1978) and Michael Sappol, A Traffic of Dead Bodies: Anatomy and Embodied Social Identity in Nineteenth-Century America (Princeton, NJ: Princeton University Press, 2004).

4. Kenneth F. Kiple and Virginia Himmelsteib King, Another Dimension to the Black Diaspora: Diet, Disease, and Racism (New York: Cambridge University Press, 1981).

5. Donald J. Elia, "Dr. Benjamin Rush and the Negro," Journal of the History of Ideas 30 (1969): 413–22.

6. Peter McCandless, Slavery, Disease, and Suffering in the Southern Lowcountry (New York: Cambridge University Press, 2014).

7. Joyce E. Chaplin, Subject Matters: Technology, Body, and Science on the Anglo-American Frontier, 1500–1676 (Cambridge, MA: Harvard University Press, 2003); and Winthrop D. Jordan, White Over Black: American Attitudes Toward the Negro, 1550– 1812 (New York: W. W. Norton & Co., 1977).

8. Roxann Wheeler, The Complexion of Race: Categories of Difference in Eighteenth-Century British Culture (Philadelphia: University of Pennsylvania Press, 2000).

9. Andrew S. Curran, The Anatomy of Blackness: Science and Slavery in an Age of Enlightenment (Baltimore, MD: Johns Hopkins Press, 2011) and "Rethinking Race History: The Role of the Albino in the French Enlightenment Life Sciences," History and Theory 48 (2009) 151–79.

10. Ibid.

11. Brent Henze, "Scientific Definition in Rhetorical Formations: Race as 'Permanent Variety' in James Cowles Prichard's Ethnology," Rhetoric Review 23 (2004): 311–31.

12. Cristinia Malcolmson, Studies of Skin Color in the Early Royal Society: Boyle, Cavendish, Swift (London: Routledge Press, 2013).

13. See Eric Charters, "Making Bodies Modern: Race, Medicine, and the Colonial Solider in the Mid-Eighteenth Century," Patterns of Prejudice 46 (2002): 214–31; Rana Hogarth, "Charity and Terror in Eighteenth-Century Jamaica: The Kingston Hospital and Asylum for Deserted 'Negroes,'" African and Black Diaspora: An International Journal 1 (2016): 1–18; and Tim Lockley, "Black Mortality in Antebellum Savannah," Social History of Medicine 26 (2013): 633–52.

14. Samuel Stanhope Smith, Essay on the Causes of Variety of Complexion and Figure in the Human Species (New-Brunswick, NJ: J. Simpson and Co., 1810). Note that this is the second edition.

15. Benjamin Rush, "Observations to Favour a Supposition that the Black Color (As It is Called) of the Negroes is Derived from the Leprosy," Transactions of the American Philosophical Association 4 (1799): 289–97. This quote came from page 289.

16. Wheeler, The Complexion of Race, 258.

17. Rush, "Observations to Favour a Supposition," 289.

18. Ibid., 290.

19. Edward Darrell Smith and later physicians in the early nineteenth century referred to similar situations as a "sympathy." See Lester King Transformations.

20. Ibid., 290.

21. Ibid.

22. Ibid., 292.

23. Ibid.

24. Ibid.

25. Ibid.

26. Ibid.

27. Ibid.

28. Ibid., 293.

29. He responds to his question by again reaching back to a historical example. Like the current inhabitants of Scotland who suffer facial changes from their ancestors high cheek bones and red hair, and the Cretins who live in the Alps who have tumors that occur in their throats because of previous ancestors' conditions, so do Africans have dark skin because of their ancestors suffering from leprosy. Ibid., 294.

30. Ibid., 294.

31. Another case in Pennsylvania further supports Rush's theory. See ibid.

32. Ibid.

33. Ibid.

34. Ibid., 295.

35. Ibid.

36. Ibid.

37. Ibid., 295–96.

38. Ibid., 296.

39. Ibid. According to the OED, it was a mucous layer below the skin.

40. Ibid., 296.

41. Ibid.

42. Ibid.

43. D'Elia, "Dr. Benjamin Rush and the Negro," 413 and 418.

44. Johnson, History of the Process, Volume 1, v.

45. Ibid., 2.

46. Ibid., iv.

47. Ibid.

48. See John C. Powers, Inventing Chemistry: Herman Boerhaave and the Reform of the Chemical Arts (Chicago: University of Chicago Press, 2012).

49. Johnson, History of the Process, Volume 1, 2.

50. Ibid.

51. Johnson, History of the Process, Volume 2, 224.

52. Ibid., 225.

53. Ibid., 227–28.

54. Ibid., 229.

55. Thomas Beddoes, Considerations on the Medicinal Use of Factitious Airs, and On the Manner of Obtaining Them in Large Quantities in Two Parts (Bristol: Bulgin and Rosser, 1794). The work is in two parts, the first by Beddoes and the second by James Watt.

56. Ibid., 32–33.

57. Ibid.

58. Ibid.

59. J. J. Virey, Natural History of the Negro Race, trans. J. H. Guenebault (Charleston: D. J. Dowling, 1837). For background information see Phillip Curtain, The Image of Africa: British Ideas and Action, 1780–1850 (Madison: University of Wisconsin Press, 1964), vol. 2, 371; Ian Federick Finseth, Shades of Green: Visions of Nature in the Literature of American Slavery, 1770–1860 (Athens: University of Georgia Press, 2009),: E. A. Driggers, (2015) "Boundary Stones: Morbid Concretions and the Chemistry of Early Nineteenth Century Medicine." Ph.D. diss., University of South Carolina, 2015,

60. John Mitchell, P. Collinson (1744) "An Essay Upon the Causes of the Different Colours of People in Different Climates; By John Mitchell, M. D. Communicated by the Royal Society by Mr. Peter Collinson, F.R.S.," Philosophical Transactions of the Royal Society of London 43 (474): 102–10.

61. Virey, Natural History of the Negro Race, 40.

62. Ibid., 40.

63. Ibid., 40.

64. Ibid., 41.

65. Ibid., 42.

66. Ibid., 47.

67. Ibid.

68. Ibid.

69. Ibid., 50.

70. Ibid., 51.

71. Ibid., 51–52.

72. Ibid., 52–53.

73. Ibid., 53.

74. Thomas Jefferson, Notes on the State of Virginia, ed. William Peden (Chapel Hill: University of North Carolina, 1955), 138.

75. Ibid., 139.

76. Pascalis, "Desultory Remarks on the Cause and Nature of the Black Colour in the Human Species; Occasioned by the Case of a White Women Suddenly Turned Black" Medical Repository of Original Essays and Intelligence 4 (1818): 366–71. This citation was found on page 419 in Linda L. Barnes Needles, Herbs, Gods, and Ghosts: China, Healing, and the West to 1848 (Cambridge, MA: Harvard University Press, 2005).

77. Pascalis, "Desultory Remarks on the Cause and Nature," 366.

78. Ibid.

79. Ibid.

80. Ibid.

81. Ibid., 367.

82. Ibid.

83. Ibid.

84. Ibid.

85. Ibid., 368.

86. Ibid.

87. Ibid.

88. Ibid.

89. Curran, Anatomy of Blackness, 259n136

90. Pascalis, "Desultory Remarks on the Cause and Nature," 368–70.

91. Ibid.

92. Ibid., 371.

93. Everard Home, "On the Black Rete Mucosum of the Negro, Being a Defence against the Scorching Effect of the Sun's Rays," Philosophical Transactions of the Royal Society of London 111 (1821): 1–6.

94. Ibid., 2.

95. Ibid., 2.

96. Ibid.

97. Ibid., 5.

98. Ibid.

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