July 5 Science History

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Learn about the history of science by reading about the significant scientific events that took place on this day in history.

1996 - First cloned mammal born.

Dolly the sheep was born and was the first successful cloned mammal. Scientists of the Roslin Institute in Scotland transfered the nucleus of an adult sheep's cell to the nucleus of an unfertilized egg cell. Dolly was the first success after 277 attempts.

1966 - George de Hevesy died.

Hevesy was a Hungarian-Swedish chemist who was awarded the 1943 Nobel Prize in Chemistry for the development of a technique to use radioisotopes to detect chemical processes in living systems. He prepared salt solutions using an isotope of lead (Pb212) and traced how plants absorbed the solution. He also discovered the element hafnium with Dick Coster in 1923.

1927 - Albrecht Kossel died.

Kossel was a German physician and chemist who was awarded the 1910 Nobel Prize in Medicine for his contributions to the understanding of nucleic acids and cell chemistry. He discovered amino acids were the basic building blocks of DNA. He also discovered the amino acids histidine, thymic acid, and agmatine.

1911 - George Johnstone Stoney died.

Stoney was an Irish physicist who was the first to suggest electric charge came in discrete units and is credited for coining the term 'electron' for the basic unit of charge. He was also one of the first to identify the vibration of individual molecules and atoms as the cause for spectral emission lines.

1891 - John Howard Northrop was born.

Northrop was an American biochemist who shares half the 1946 Nobel Prize in Chemistry with Wendell Stanley for their technique of purifying and crystallizing enzymes and virus proteins. The other half of the Prize went to James Sumner for the discovery that it was possible to crystallize enzymes. This is important because once a substance is crystallized, its molecular structure can be determined.

1888 - Herbert Spencer Gasser was born.

Gasser was an American physiologist who shares the 1944 Nobel Prize in Medicine with Joseph Erlanger for their research into the action potentials in nerve fibers. Action potentials are self-generating electrochemical pulse that allow nerve cells to transmit a signal over a distance. They discovered there were different fibers in nerves that had three different fibers that would conduct the potential from a stimulus at different rates. This led to the theory that one type of fiber conducts pain signals and others conduct motor control signals.

1867 - Andrew Ellicott Douglass was born.

Douglass developed the study of dendrochronology, or the study of dating wood by the tree's ring patterns. He noticed tree rings were closer together during dry years and these years also had increased sunspot activity.

1833 - Joseph-Nicéphore Niépce died.

Niépce was a French inventor who is considered the inventor of photography. He invented a process called heliography or 'sun writing' that used bitumen dissolved in lavender oil spread onto a sheet of paper. The paper was used in a camera obscura setup and exposed for up to eight hours. The paper would then be washed again in lavender oil to remove the unexposed sections of bitumen to show the image.

1826 - Joseph-Louis Proust died.

Proust was a French chemist who proved that the relative quantities of the elements that make up a chemical compound is constant, regardless of the component's source. This is referred to as Proust's law or the law of definite proportions. His later work involved the study of sugars. He showed the sugar in grapes is identical to the sugar in honey.

1820 - William John Macquorn Rankine was born.

Rankine was a Scottish engineer and physicist who was a pioneer of thermodynamics. He developed a theory relating the pressure of steam to its temperature in a steam engine. He determined the specific heat of steam had a negative value and described the dynamics involved in a steam engine in terms of energy instead of forces and motion. The Rankine absolute temperature scale based on the Fahrenheit temperature scale is named in his honor.
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