July 21: Georg Brandt, Harriet Brooks identifies nucleus recoil, Yrjö Väisälä, Ian Donald uses ultrasound

Georg Brandt

Swedish chemist Georg Rushd Brandt was born on 21 July 1694. Brand was the first person to isolate and identify in 1730 the element he named named cobalt. He published in 1733 his findings on the composition and solubility of arsenic compounds, then researched antimony, bismuth, mercury and zinc. His work on methods of producing hydrochloric, nitric and sulfuric acids was published in 1741 and 1743.

Brandt was one of the first chemists to completely forswear alchemy and devoted his later years to exposing fraudulent alchemical processes claiming to produce gold.


Harriet Brooks identifies atomic nucleus recoil

Harriet brooks
Harriet Brooks (Creative Commons)

Today in 1904 the the journal Nature published a letter from Canadian physicist Harriet Brooks in which she identified a peculiar type of volatility shown by an active deposit of radium. This was later shown to be “due to the recoil of radium B from the active surface accompanying the expulsion of an alpha-particle from Radium A” in the words of New Zealand physicist Ernest Rutherford. Brooks is widely-acknowledged as the first person to observe the recoil of an atomic nucleus as particles are emitted during radioactive decay.


Yrjö Väisälä

We remember Finnish meteorologist and astronomer Yrjö Väisälä, who died on this day in 1971 at the age of 79 and who was regarded as the “father of space research in Finland”. As early as 1946, he had suggested that geodetic triangulation, at that time being done with rockets or balloons with onboard flashes, could better be accomplished by artificial satellites. The lunar crater Väisälä is named after him, as are the minor planets 1573 Väisälä and 2804 Yrjö.


Ian Donald diagnoses using ultrasound

In 1955, Englishman Ian Donald made his first investigation into the use of ultrasound as a medical diagnostic tool. At the research department of the boilermaker Babock and Wilcox at Renfrew, Scotland, he used an industrial ultrasonic metal flaw detector to image tumours from human organs. Donald knew sonar from his service in WW II, which was similar to the reflected ultrasound used to image the internal structure of the sample tissues.

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