Background

Clausius was born on January 2, 1822, in Köslin, Pomerania (present-day Koszalin, Poland), the sixth son of the 18 children of the Reverend C. E. G. Clausius, a Lutheran pastor and councilor of the Royal Government School Board in Köslin.

Education

Young Clausius received much of his primary and secondary education in the private school which his father established in Uckermünde.

After graduating from the gymnasium in Stettin, Clausius enrolled at the University of Berlin, and in 1844 he obtained his teacher's certificate. He received his doctoral degree in 1848 from the University of Halle with a dissertation which gave for the first time the explanation of the blue sky and red sunset in terms of the selective reflection of various wavelengths of light by particles present in the atmosphere.

Career

In 1850 Clausius became a professor of physics at the Royal Artillery and Engineering School in Berlin and also obtained the rank of Privatdozent at the University of Berlin. He presented his paper "On the Motive Power of Heat and on the Laws Which Can Be Deduced from It for the Theory of Heat" in 1850. Clausius insisted that the "new theory" could only be a mechanical one. More importantly, he showed that it was quite consistent with the mechanical theory to assume that when work was done by heat one part of the heat was "lost," or rather was transformed into work. This part of the heat and the other part which was rejected into the cold reservoir of the engine stood, in Clausius's words, in a "certain definite relation to the quantity of work produced."

Two subsequent papers published in 1851 by Clausius clarified merely some details of his first memoir, but in 1854 he confronted once more the fundamentals. What became known as his fourth memoir carried the title "On a Modified Form of the Second Fundamental Theorem in the Mechanical Theory of Heat." Meanwhile, he moved to Zürich to serve as professor of physics at the Swiss Federal Technical Institute. Two years later he also assumed a professorship at the University of Zürich.

The scientific fruits of Clausius's first years in Zürich related to the kinetic theory of gases. Clausius achieved his task in two papers: "On the Kind of Motion Which We Call Warmth" (1857) and "On the Average Length of Paths Which Are Traversed by Single Molecules in the Molecular Motion of Gaseous Bodies" (1858). From the assumption that molecules move in a straight path, Clausius calculated the average velocity of hydrogen molecules at normal temperature and pressure. Because the value, about 2,000 meters per second, seemed to contradict the low rate of gaseous diffusion, Clausius offered as explanation the important notion of the free mean path of molecules.

A few years later, in 1862, Clausius published his paper "On the Thermal Conductivity of Gaseous Bodies, " in which he successfully derived from theoretical considerations the experimentally known data in question. He deserved indeed the praises heaped on him by Maxwell, who referred to Clausius as the first who "gave us precise ideas about the motion of agitation of molecules." Maxwell also described the adoption of mechanical principles to molecular studies as being "to a great extent the work of Prof. Clausius."

The year 1862 also saw the return of Clausius's full attention to thermodynamics. The results spoke for themselves. In the paper known as his sixth memoir, "On the Application of the Theorem of the Equivalence of Transformations to Interior Work," he concluded that it was "impossible practically to arrive at the absolute zero of temperature by any alteration of the condition of a body."

On April 24, 1865, Clausius read before the Philosophical Society of Zürich his best-remembered paper, or ninth memoir, "On Several Convenient Forms of the Fundamental Equations of the Mechanical Theory of Heat." In it the word "entropy" was used for the first time.

In 1869 Clausius accepted an invitation to become a professor of physics at the University of Bonn after having spent 2 years in the same capacity at the University of Würzburg. The University of Bonn represented the last phase of Clausius's academic career. There he wrote in 1870 his last important paper on thermodynamics, which contained the notion of virial. In 1876 he published a second, considerably enlarged and revised version of what was mainly a collection of his memoirs which had been printed in 1864 under the title Abhandlungen über die mechanische Wärmetheorie. The new edition, entitled Die mechanische Wärmetheorie (The Mechanical Theory of Heat), was for several decades the standard for textbooks on thermodynamics. The second part of the book deals with the analysis of electrical phenomena on the basis of mechanical principles, a topic which dominated Clausius's attention in Bonn.

In the summer of 1886, he began to show symptoms of acute anemia. Nevertheless, he carried on with the work of seeing to print the third edition of his Wärmetheorie, and he even held examinations from his sickbed. He was the embodiment of sincerity and conscientiousness to the end, which came on August 24, 1888.

Achievements

• 

  Clausius is best known for formulating the second law of thermodynamics and is credited with making thermodynamics a science. Clausius also gave the first mathematical version of the concept of entropy, and also gave it its name.

Works

More photos

• book

  • Abhandlungen Über Die Mechanische Wärmetheorie

    (German Edition)

  • Die Potentialfunction und das Potential: Ein Beitrag zur Mathematischen Physik

    (German Edition)

  • Die Kinetische Theorie der Gase

    (German Edition)

  • The Mechanical Theory of Heat: With Its Applications to the Steam-Engine and to the Physical Properties of Bodies 1867

Views

Quotations: "Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time."

"I have intentionally formed the word entropy so as to be as similar as possible to the word energy; for the two magnitudes to be denoted by these words are so nearly allied in their physical meanings, that a certain similarity in designation appears to be desirable."

"If for the entire universe we conceive the same magnitude to be determined, consistently and with due regard to all circumstances, which for a single body I have called entropy, and if at the same time we introduce the other and simpler conception of energy, we may express in the following manner the fundamental laws of the universe which correspond to the two fundamental theorems of the mechanical theory of heat. The energy of the universe is constant. The entropy of the universe tends to a maximum."

Membership

• Institution of Engineers and Shipbuilders , United Kingdom

  1859

• Royal Society of London , United Kingdom

  1879

• Royal Swedish Academy of Sciences , Sweden

  1878

• Accademia Nazionale dei Lincei , Italy

  1880

• German Academy of Sciences Leopoldina , Germany

  1880

• Royal Netherlands Academy of Arts and Sciences , Netherlands

  1886

Connections

Clausius' first wife, Adelheid Rimpham, died in childbirth in 1875, leaving him to raise their six children. In 1886, he married Sophie Sack, and then had another child.

Father:

C. E. G. Clausius

He was a Lutheran pastor and councilor of the Royal Government School Board in Köslin.

Spouse:

Sophie Sack

ex-spouse:

Adelheid Rimpham

colleague:

Sadi Carnot

References

• Rudolf Clausius
• Dictionary of Scientific Biography Volume 3
  1971