Wednesday, September 22, 2021

My ether was acid

‘The substance dissolves much more readily in Ether than in Alcohol. A hot solution of Ether deposits crystals as it cools. A glass rod dipped in it and exposed to the air is instantly covered with the substance in white powder from the evaporation of the ether. Query acidity of solution? My ether was acid.’ This is an early entry in the prosaic scientific notebooks kept by Michael Faraday, a great English scientist born 230 years ago today. Although all the entries - spanning over 40 years - are technical in the extreme, full of scientific notation, they were first published, in seven volumes in the 1930s, as Faraday’s Diary.

Faraday was born on 22 September 1791 in what is now Southwark in south London. His father had been apprenticed to a blacksmith, and young Michael received little education before he was apprenticed to a bookbinder and bookseller at the age of 14. The position gave him access to books, and he read avidly, trying to improve himself and to learn about science, especially electricity.

In 1812, Faraday attended lectures given by the chemist Humphry Davy at the Royal Institution. Subsequently, Faraday wrote to Davy asking for a job, which led to him being appointed as a chemical assistant at the Royal Institution. Davy also took Faraday with him on an 18 month tour of Europe, during which time they met many prominent scientists. In 1821, he married Sarah Barnard, but they were to have no children. That same year, he published his work on electromagnetic rotation (the principle behind the electric motor); and in 1826 he founded the Royal Institution’s Friday Evening Discourses and Christmas Lectures, giving many of the lectures himself.

In 1831, Faraday discovered electromagnetic induction, the principle behind the electric transformer and generator, and thereafter he continued to help pave the way for the widespread development of electricity as an accessible source of energy. He is credited with coining many now-familiar words, such as electrode, cathode and ion. He was appointed Scientific Adviser to the Admiralty in 1829, was Professor of Chemistry at the Royal Military Academy, Woolwich, between 1830 and 1851 and Scientific Adviser to Trinity House from 1836 to 1865. He died in 1867 at Hampton Court (where he had been given official lodgings in recognition of his contribution to science). Further information is available at Wikipedia, the Royal Institution, the BBC, Encyclopaedia Britannica and the Science History Institute.

Faraday kept very detailed observations about his work and experiments for over 40 years. These scientific notebooks or diaries were bequeathed by him to the Royal Institution which then oversaw their publication - as Faraday’s Diary - in seven volumes in the 1930s. In 2008, the institution reprinted the whole series ‘as edited by Thomas Martin with index, photographs and thousands of illustrations in Faraday’s own hand’. According to institution: ‘Faraday is generally held to be one of the greatest of all experimental philosophers. Nearly every science is in his debt: and some sciences owe their existence mainly to his work. The liquefaction of gases, benzene, electro-magnetic induction, specific inductive capacity, lines of force, magnetic conduction or permeability, the dark discharge, anode, cathode, magneto-optics, electro-chemical equivalent; all these terms suggest fundamental researches which he made, and many of them were called into existence in order to describe his discoveries.’

The new edition can be previewed here, and some volumes of the first edition are freely available at Internet Archive. However, although titled ‘diary’ the work would be better described as scientific notebooks. There are no entries with domestic or personal details, for example, they are all focused entirely on his scientific work - here’s a couple of sample extracts from early on in the first volume, and a screenshot of one double-page spread in the third volume.

3 October 1820
‘Put Oleft. oil into a retort - exhausted - introduced chlorine- exposed to light - after the action introduced a little water - this absorbed the M.A. Gas and made a fresh vacuum - let in more chlorine and again exposed to light, shaking the retort - fresh action, then more chlorine - when the substance all changed, filled up the retort with water so as to wash out the acid well - repeated washing - dissolved the substance in alcohol and crystallised. This saves exhausting by the air pump which is very injurious to the instrument.’

5 October 1820
‘The crystals of the substance (from a strong alcoholic solution) were very brittle and crumbled into a white powder very easily. It is on this account difficult to preserve them. They were taken out of the Alcohol, dried by pressure between filtering paper, exposed to the air for half an hour and then put into a bottle. The substance was then a white dry powder.

The Alcoholic solution spontaneously evaporated; left crystals of the substance but they evaporated also in an hour or two afterwards.

The crystals by sublimation are much tougher than those formed from solutions.

The substance dissolves much more readily in Ether than in Alcohol. A hot solution of Ether deposits crystals as it cools. A glass rod dipped in it and exposed to the air is instantly covered with the substance in white powder from the evaporation of the ether.

Query acidity of solution? My ether was acid.

A drop of the etherial solution put on a glass plate instantly expands, evaporates and its surface becomes covered with square crystalline plates, the crystals being dendritic and their axes lying parallel to the diagonals of the square. In this way the substance may be got very dry.

Water dissolves but a very small portion of it when boiled with it.

The solution of it in Alcohol is not acid - and is not precipitated by Nitrate of silver.

Solution of potash does not dissolve it perceptibly by boiling -  nor Ammonia (strong). Muriatic acid does act on it.

Nitric acid (strong) boiled upon it dissolves a portion but does not decompose it: as it cools the substance deposits again unaltered. The concentrated acid diluted lets more of the substance fall; and then filtered and tested by N. of Silver gave no precipitate - hence no chlorine separated from the substance by it.

Put into strong Sul. Acid it very slowly sinks to the bottom, hence its S.G.; boiled with the acid the acid became brown, probably from some little pieces of dirt that were mixed with the substance. The substance sublimed from and through the acid unaltered and the acid tested contained no Mur. Acid or chlorine. It was not precipitated by water, hence no substance dissolved.’

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