Joseph Black
1728 - 1799

"I was born at Bordeaux April 16th, 1728. My father was a merchant settled there, but born in Ireland and the son of a citizen of Belfast of Scottish extraction.  My father's residence at Bordeaux was in the suburb called the Chartron, and he had also a farm and country house and vineyard on the other side of the river on a hill called Lormont which commands a fine prospect of the river and city." 1

Education.   Joseph Black's mother taught all of her children (8 sons and 5 daughters) to read English.  Black left home at age 12 to study Latin and Greek in Belfast where he lived with relatives.  Black was educated in medicine at Glasgow University.  Around 1750 he moved to Edinburgh, and in June 1754 presented his inaugural dissertation, On the Acid Humour Arising from Food and Magnesia alba.2 The thesis dealt principally with value of magnesia as an antacid.

Professor Black. Joseph Black began academic life at age 28 as professor of anatomy and lecturer of chemistry 1756.  Black spent most of his professional life as professor of chemistry in Edinburgh from 1766 - 1799.  In Black's time, chemistry was regarded as a subordinate of medicine its sole purpose was to provide remedies for treatment of disease.  Black was a very popular lecturer — attracting audiences of several hundred students, often performing lecture experiments.

"Many were induced, by the report of his students, to attend his courses, without having any particular relish for chemical knowledge."3

    Black's lecture demonstrations included several that chemistry teachers still do to this day — including pouring 'fixed air' over a candle from a jar, and exhaling through a tube into limewater.  Late in Black's life, Lavoisier presented his oxygen theory, which Black quickly accepted and taught to his students rather than the traditional phlogiston theory.

    Black died on November 10, 1799 peacefully seated in his chair at the University of Edinburgh.

Fixed Air.  Black showed that magnesia alba (now xMgCO3, yMg(OH)2, zH2O), when heated gave off water plus 'fixed air' (now CO2) — an 'air' previously described by van Helmont as gas sylvestre.  The residue, calcined magnesia (now MgO), was lighter and more alkaline.  Limestone (now CaCO3) did the same, but Black was able to study this sequence quantitatively:

limestone + heat yields fixed air + quicklime

[now: CaCO3(s)  CO2(g) + CaO(s)]

quicklime slaked with water and then boiled with mild alkali(now K2CO3),
the alkali becomes caustic and original weight of limestone restored

[now: CaO(s) + H2O(l)   Ca(OH)2(s, aq)

Ca(OH)2(s, aq) + K2CO3 CaCO3(s) + 2 KOH(aq)]

"If quicklime is mixed with a dissolved alkali it shows an attraction for fixed air superior to that of the alkali.  It robs this salt of its air and thereby becomes mild itself...."3

Lasting accomplishments.

•  Black established for the first time that a gas could combine with a solid, previously believed to be impossible.

•  Black recognized that there were various types of airs (air had been considered an element.)  'Fixed air' was a definite chemical entity different from air.  This completely changed the understanding of the chemical nature of gases and ushered in the era of pneumatic chemistry.

•  Black is considered the 'founder of calorimetry.'  His pioneering work with latent heats of fusion and evaporation and with what is now call specific heat and heat capacity proved invaluable to James Watt who used the information to improve the steam engine.  (In Black's time, heat was considered a kind of matter.)

•  Perhaps Black's most important contribution even escaped his own knowing.  Black explained his observations without reference to the phlogiston theory.  This impressed Lavoisier and provided him with an important clue as he formulated his oxygen theory.


1 from autobiographical memorandum, The Life and Letters of Joseph Black, by Sir William Ramsay, Constable, (1918)

2 translation from Latin appears in J Chem Ed (1935), xii, 225, 268

3 from the only biography of Black, written by his successor Robison and printed in A Short History of Chemistry, J. R. Partington, 3rd edition, (1957)

(This page last updated 25 September 2001)