Electroscope and thermal water analysis - April's object of the month

 

 

This month, we highlight the Chéneveau-Laborde apparatus (MUHNAC-UL001297), an instrument used to measure radioactivity. This object is engraved in the eyepiece of the microscope "DEYROLLE" and bears a handwritten label from the Physics Department of the Faculty of Sciences, with the inscription "LAB.41".
This apparatus essentially consists of a single-sheet electroscope suspended from an insulating piece connected by a metallic conductor to the atmosphere of a closed container containing the radioactive sample; the sheet moves away from its support at a given angle and the angular variation is read through a microscope eyepiece fitted with a micrometer. The two coefficients time and angular distance are used to measure the radioactive intensity of the analyzed substance.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

This is an electroscope similar to the one used by Charles Lepierre (1867-1945), to measure the radioactive content in the waters of the main Portuguese thermal springs, whose potentialities his research helped to recognise at the time. The results (link) were published by Instituto de Hidrologia in several booklets. Cucos (1896), Funchal (1900), Guimarães (1900), S. Vicente (1910), Amieira (1911), Vidago (1913), Vizela (1914), Melgaço (1915), Alardo (1916), Furnas (Açores) (1917), Carvalhelhos (1919), Monte Real (1920), Santa Marta (Ericeira) (1920), Piedade, Luso (link), Caldas da Rainha, Estoril, Verride (1921), Vila Verde dos Francos (1922), Curia (1925), Gerês (1925 e 1927), Águas de Moura (1927), Caldelas (1927), Alcaçarias do Duque em Lisboa (1927), Aregos (1928), Monchique (1928) (link), S. Pedro do Sul (1929), Caria, (1930) e Foz da Certã (1932).

This chemist was in Lisbon between 1888 and 1889 as head of Mineral Chemistry at the Escola Politécnica and preparator of Chemical Technology at the Instituto Industrial.

Having graduated in Paris from the École de Physique et Chimie Industrielles in 1887, Lepierre was hired the following year by the Lisbon Polytechnic School as a preparer for the Chemistry Chairs. This hiring took place in the context of an incident in the Laboratories of this School, the consequent suspension of practical teaching by the lecturer José Júlio Bettencourt Rodrigues (1845-1893) and his insistence to the Board of this School for the hiring of experienced staff and improvement works in the Laboratorio Chimico, adapting it to a more experimental and pedagogical component. In the proceedings of the School Council of the Polytechnic School of Lisbon of 1st October 1888, one can read: "The lecturer of the 6th chair is authorised to pay from the endowment of the chair [...], the sum of 18 000 réis per month to the preparer of the Industrial Institute, Carlos Lepierre, on provisional service at the School and responsible for assisting the lecturer in the lessons of the Chemistry course".

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Charles Lepierre left for Coimbra where he worked intensively (1889-1911) as a teacher at the Avelar Brotero Industrial School and fundamentally at the University (Microbiology Laboratory).
In 1911 he returned to Lisbon, where he taught Chemistry at the former Industrial Institute (now Instituto Superior Técnico) and at the Institute of Hydrology from 1919 onwards. He devoted himself to applied science studies with repercussions on Portuguese economic life: canned food, olive oil and milk.

He assumed other institutional positions, namely member of the Higher Council of Mines and Geological Services and as director of the Laboratory of the Portuguese Institute for Fish Preserves.

He also held the position of consulting engineer at the Société Urane-Radium plant, controlled by the Burnay Bank, for 20 years, from 1917 until his retirement, to direct the work of the uranium ore treatment plant in the village of Barracão, in Beira Alta. Lepierre had been a student of Pierre Curie and his hiring would prove to be essential to make Portugal an important supplier of radium for the Curie couple, as the Austrian government had suspended, in 1903, the export of uranium ore from the mines of Joachimsthal, in Bohemia, to France, ore which had allowed the isolation and identification of two new chemical elements, polonium and radium, by Marie and Pierre Curie, for which, both were awarded the Nobel Prize in Physics in 1903, and in 1911 the Nobel Prize in Chemistry to Marie.

The Barracão mine had been in operation since 1908, but Lepierre optimised the process, determining the quality and quantity of the material extracted.

 

WATERS and ROCKS

The chemical composition of water is very variable and depends on the composition of the rocks it passes through before reaching the source or a borehole. In Portugal, geodiversity is great; therefore, the chemical composition of groundwaters is very diverse.

 

 

 

 

 

 

 

 

 

Alkaline waters / Nepheline syenite
Waters are alkaline when they circulate through rocks composed of easily alterable minerals, as is the case of rocks composed of minerals with little silica.  This is the case of Monchique's water, that circulates in nepheline syenites, where quartz is absent and nepheline predominates.

 

 

 

 

 

 

 

 

 

 

 

Calcareous waters/ Limestone
When they pass through limestone, which is fundamentally made up of calcium carbonate, the waters are mainly calcareous.  This is the case of Cruzeiro water, with a calcium-magnesium bicarbonate composition, since in its composition the predominant ions are the bicarbonate anion and the calcium and magnesium cations.
 

 

 

 

 

 

 

 

Low mineralized waters / Quartzite
Sometimes the waters are very little mineralized, almost rainwater. This happens when they pass through rocks made up of minerals that are not very soluble, such as quartzite (rock composed fundamentally of silica/quartz). Examples are the waters of Luso and Vitalis, which flow through quartzite rocks.

 

 

 

 

 

 

 

 

 

Carbonic waters / Associated tectonics
Acidic waters / Granite

Carbonated waters (sparkling waters) are waters that have free CO2(g) in their composition. They are usually associated with areas of active tectonics, which allows the gas to rise from depth. Well-known examples are the waters of Vidago and Pedras Salgadas. These waters are slightly acidic due to the presence of CO2(g) and because they circulate in granitic rocks, acquiring a sodic bicarbonate composition by dissolving the constituent feldspars of the granites.
Water circulating through granites may present some radioactivity if those rocks are rich in uranium minerals, as is the case of Fadagosa de Nisa water.

 

Text by: Branca Moriés, Bibliotecas/Arquivo Histórico, IICT & Museus da ULisboa | Elisa Campos, Faculdade de Ciências Médicas da UNL | Liliana Póvoas, Curadora convidada Coleções Geológicas MUHNAC | Rosário Carvalho, Faculty of Sciences of the University of Lisbon | Maria do Carmo Elvas, Núcleo de Património e Coleções, MUHNAC
Photo by: Catarina Mateus, João Paulo Lopes, Maria do Carmo Elvas

 

Electroscope
Maker: Les fils d'Émile Deyrolle
Provenance: Physics Department of the Faculty of Sciences of the University of Lisbon                                                                                                         
MUHNAC- UL001297