1838年にWilliam HenryFox Talbotが行ったのと同じようなテストです。
このヨウ素、何と日本が世界の３０％を生産していました。 チリが６５％なので、この２カ国で世界の需要をほぼまかなっています。 ヨウ素は日本の大切な天然資源なのでした。
The following is Talbot note.
“At the close of the year 1838, I discovered a remarkable fact of quite a new kind. Having spread a piece of silver leaf on a pane of glass, and thrown a particle of iodine upon it, I observed that coloured rings formed themselves around the central particle, especially if the glass was slightly warmed. The coloured rings I had no difficulty in attributing to the formation of infinitely thin layers or strata of iodide of silver; but a most unexpected phenomenon occurred when the silver plate was brought into the light by placing it near a window. For then the coloured rings shortly began to change their colours, and assumed other and quite unusual tints, such as are never seen in the “the colours of thin plates.” For instance, the part of the silver plate which at first shone with a pale yellow colour, was changed to a dark olive green when brought into the daylight. This change was not very rapid: it was much less rapid than the changes of some of the sensitive papers which I had been in the habit of employing, and therefore, after having admired the beauty of this new phenomenon, I laid the specimens by, for a time, to see whether they would preserve the same appearance, or would undergo any further alteration.”
Private “ohanami” (cherry blossom viewing).
I did Talbot’s ring test today, as the same as William HenryFox Talbot did in 1839.
Place a piece of iodine in the center of polished silver plate and see how the color changes. The 3rd cycle yellow will react to the sunlight most but I still cannot make out the best color when I shoot the daguerreotype.
I didn’t know that Japan produces about 30% of world iodine consumption. And Chilie does about 65% so these 2 countries mostly cover the worldwide demand.
The iodine is one of the most valuable natural resource in Japan.