This is the papaer where Marie Curie announced the discovery of Polonium.
Here's a link with OCR on the French Wikisource: fr.wikisource.org/wiki/%C5%92uvres_de_Pierre_Curie/23. It's from a 1908 collection of works, but it is the exact same paper.
First a recap of previous work:Note the cute terminology "Becquerel rays", which were only later understood to be electromagnetic radiation now known as gamma rays.
Some minerals containing uranium and thorium (pitchblende, chalcolite, uranite) are very active from the point of view of the emission of Becquerel rays. In a previous work, one of us showed that their activity is even greater than that of uranium and thorium, and expressed the opinion that this effect was due to some other very active substance contained in small quantities in these minerals.
Then some more recapitulation of the previously discussed groundbreaking idea that only atom counts matter for radioactivity, regardless of their chemical configuration as in fluorescence:
The study of compounds of uranium and thorium had shown, in fact, that the property of emitting rays which make air conductive and which act on photographic plates is a specific property of uranium and thorium which is found in all compounds of these metals, all the more weakened as the proportion of active metal in the compound is itself lower. The physical state of the substances seems to have a completely secondary importance. Various experiments have shown that the state of mixture of the substances seems to act only by varying the proportion of active bodies and the absorption produced by the inert substances. Certain causes (such as the presence of impurities) which act so powerfully on phosphorescence or fluorescence are therefore here completely without action. It therefore becomes very probable that if certain minerals are more active than uranium and thorium, it is because they contain a substance more active than these metals.
Then the key innovation: they used radioactivity measures to guide their purification work:
We have sought to isolate this substance in pitchblende, and experience has confirmed the above predictions.Our chemical research has been constantly guided by the control of the radiant activity of the products separated at each operation. Each product is placed on one of the plates of a condenser, and the conductivity acquired by the air is measured using an electrometer and a piezoelectric quartz, as in the work cited above. We thus have not only an indication but a number which accounts for the richness of the product in active substance.
Next they describe in high level their separation process, and I can't understand anything. But that's OK
Finally towards the end, bombs are dropped:
- the new elemnt is next to bismuth. If you stop now and look at a periodic table, you will see that bismuth is exactly one element before polonium
- "simple bodies" is their cute terminology for atoms, whose existence at the time not yet full aknowledged Section "History of the atomic theory"
- we call it polonium
By carrying out these various operations, we obtain increasingly active products. Finally, we obtained a substance whose activity is about 400 times greater than that of uranium.We have sought, among the bodies currently known, to see if there are any active ones. We have examined compounds of almost all simple bodies; thanks to the great kindness of several chemists, we have had samples of the rarest substances. Uranium and thorium are the only ones clearly active, tantalum is perhaps very weakly so.
They managed to purify it enough to look at the emission spectrum and it seems novel:
Mr. Demarçay was kind enough to examine the spectrum of the body that we are studying. He was unable to distinguish any characteristic line apart from those due to impurities. This fact does not support the idea of the existence of a new metal. However, Mr. Demarçay pointed out to us that uranium, thorium and tantalum offer particular spectra, formed of innumerable lines, very fine, difficult to perceive.
And once again, our radiation-based analytical chemistry technique is new:
Allow us to note that if the existence of a new element is confirmed, this discovery will be uniquely attributable to the new method of detection that Becquerel rays provide.
superuser.com/questions/420885/is-there-a-face-recognition-command-line-tool/1852394#1852394 played with the
face_recognition Python package: github.com/ageitgey/face_recognition Cute CLI API, but disappointing accuracy. Also at:Thanks Adam Geitgey for putting that repo up.
Under Section "Publication by Marie Curie" I did a quick overview of the papers in which Marie Curie and collaborators publish the existence of new elements polonium and radium. Both are very understandable (except the chemistry), and have some cute terminology. I also cited those papers on her Wikipedia page: en.wikipedia.org/w/index.php?title=Marie_Curie&diff=1240252528&oldid=1238097626 Another good exercise in "old paper finding" + "Wikipedia markup/rules" as I looked at the Comptes rendus de l'Académie des Sciences a bit.
The RaLa Experiment by Our Own Devices
. Source. 
Do all gamma rays have the same energy during a given nuclear reaction? Updated 2025-04-18 +Created 2024-08-14
The following cobalt-60 diagrams suggest that some lines are clearly visible in specific nuclear reactions:
Also this one:
They are stopped by:Therefore, alpha emitters are not too dangerous unless ingested.
This one contains a PDF with OCR: archive.org/details/ComptesRendusAcademieDesSciences0127/page/n5/mode/2up
Gun-type fission weapons don't work with Plutonium-239 because of the presence of Plutonium-240 as an impurity which leads to fizzle.
Good mentions at: youtu.be/dgBDvnqMkT4?t=252
A nuclear reactor made to produce specific isotopes rather than just consume fissile material to produce electrical power. The most notably application being to produce Plutonium-239 for nuclear weapons from Uranium-238 being irradiated from Uranium-235-created fission.
Weapon grade Plutonium is cheaper than weapon grade Uranium Updated 2025-04-18 +Created 2024-08-14
Because you can generate plutonium-239 from uranium-238 in a breeder reactor, and then separate the plutonium-239 from the Uranium simply by using chemistry methods because you've created an element with different valence electrons.
Isn't it somewhat funny that it is easier to purify a synthetic element than a naturally occurring one?
This isotope shows up as an inevitable contaminant in Plutonium-239 for nuclear weapons, because it emits neutrons too fast and makes it harder to assemble the critical mass without fizzle.
It is the presence of this contaminant that made implosion-type fission weapon a necessity: Section "Gun-type fission weapons don't work with plutonium".
There are unlisted articles, also show them or only show them.