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Updated: June 21, 2025
Notwithstanding the fact that the tube was covered with an opaque shield, so that no light could be transmitted, Professor Röntgen noticed that changes in the barium paper were taking place, as though it were exposed to the action of light! Black lines appeared on the paper, showing that the surface was undergoing chemical change from the action of some invisible and hitherto unknown force!
The first thing I found was a wooden stool, on which I resolved to sit. Then I found the shelf on the side next the tube, and then the sheet of paper prepared with barium platino-cyanide.
Tons of uranium residues have to be treated in order to obtain a few decigrammes of pure salts of radium. Radium is characterised by a special spectrum, and its atomic weight, as determined by Madame Curie, is 225; it is consequently the higher homologue of barium in one of the groups of Mendeléef.
A mixture of pure lithium chloride and barium bromide weighing 0.6 gram is treated with 45.15 cubic centimeters of 0.2017 N silver nitrate, and the excess titrated with 25 cc. of 0.1 N KSCN solution, using ferric alum as an indicator. Calculate the percentage of bromine in the sample. !Answer!: 40.11%.
Ångström and Thalén pushed the coincidences to 450 for iron, while, according to the same excellent investigators, the following numbers express the coincidences, in the case of the respective metals to which they are attached: Calcium 75 Barium 11 Magnesium 4 Manganese 57 Titanium 118 Chromium 18 Nickel 33 Cobalt 19 Hydrogen 4 Aluminium 2 Zinc 2 Copper 7
Many white pigments, such as zinc oxide, zinc sulphide, calcium carbonate, barium carbonate, calcium sulphate, lead white, etc., turn brown to black, and no white lacquer can be obtained with them. Red Pigments. Vermilion and red oxide of iron. These two are used for the red lacquer, but vermilion should be stoved at a low temperature. Blue Pigment. Prussian blue. Yellow Pigments.
Utensils lacquered with this lacquer are dried for about an hour at 130° to 140° C. Red. Vermilion, 10 parts; finished lacquer, 4; solvent, 2. This lacquer is dried for about an hour at 130° to 140° C. Khaki or Dirty Yellow. Barium sulphate, 100 parts; chromic oxide, 3; finished lacquer, 20 to 25; solvent, 15. This lacquer is dried for about half an hour at 160° C. Green.
"I was working with a Crookes tube covered by a shield of black cardboard. A piece of barium platino-cyanide paper lay on the bench there. I had been passing a current through the tube, and I noticed a peculiar black line across the paper." "What of that?" "The effect was one which could only be produced, in ordinary parlance, by the passage of light.
Salts of radium have in general the same chemical properties as the corresponding salts of barium, but are distinguished from them by the differences of solubility which allow of their separation, and by their enormous activity, which is about a hundred thousand times greater than that of uranium. Radium produces various chemical and some very intense physiological reactions.
First of all men after the discoverer, Robert saw the gold mass, when the electrodes were again applied to it, change swiftly and successively to barium, to tin, to silver, to copper, to iron. He saw the long white electric sparks change to crimson with the strontium, to purple with the potassium, to yellow with the manganese.
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