{"id":4683,"date":"2025-04-02T17:00:00","date_gmt":"2025-04-02T22:00:00","guid":{"rendered":"https:\/\/patents.harnessip.com\/?p=4683"},"modified":"2025-04-02T18:58:47","modified_gmt":"2025-04-02T23:58:47","slug":"april-2-2025","status":"publish","type":"post","link":"https:\/\/patents.harnessip.com\/?p=4683","title":{"rendered":"April 2, 2025"},"content":{"rendered":"\n<p>On April 2, 1889, Charles M. Hall received U.S. Patent No. 400664 on a Process of Reducing Alumina from its Fluoride Salts by Electrolysis:<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><a href=\"https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-1.png\"><img loading=\"lazy\" decoding=\"async\" width=\"493\" height=\"808\" src=\"https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-1.png\" alt=\"\" class=\"wp-image-4684\" srcset=\"https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-1.png 493w, https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-1-183x300.png 183w\" sizes=\"auto, (max-width: 493px) 100vw, 493px\" \/><\/a><\/figure>\n<\/div>\n\n\n<p>before Hall&#8217;s invention, aluminum was very expensive to produce &#8212; so much so that its price was near that of precious metals such as silver and gold.  When the Washington Monument was completed at the capping ceremony of December 6, 1884, a pyramid of solid aluminum 22.6 cm high, 3.9 cm at its base, weighing 2.85 kg, and costing $225 was installed at the top, forming part of the monument&#8217;s lighting protection system. <\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><a href=\"https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-2.png\"><img loading=\"lazy\" decoding=\"async\" width=\"349\" height=\"342\" src=\"https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-2.png\" alt=\"\" class=\"wp-image-4685\" srcset=\"https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-2.png 349w, https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-2-300x294.png 300w, https:\/\/patents.harnessip.com\/wp-content\/uploads\/2025\/04\/image-2-306x300.png 306w\" sizes=\"auto, (max-width: 349px) 100vw, 349px\" \/><\/a><\/figure>\n<\/div>\n\n\n<p> <\/p>\n","protected":false},"excerpt":{"rendered":"<p>On April 2, 1889, Charles M. Hall received U.S. Patent No. 400664 on a Process of Reducing Alumina from its Fluoride Salts by Electrolysis: before Hall&#8217;s invention, aluminum was very expensive to produce &#8212; so much so that its price &hellip; <a href=\"https:\/\/patents.harnessip.com\/?p=4683\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18],"tags":[],"class_list":["post-4683","post","type-post","status-publish","format-standard","hentry","category-patent-of-the-day"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=\/wp\/v2\/posts\/4683","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4683"}],"version-history":[{"count":1,"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=\/wp\/v2\/posts\/4683\/revisions"}],"predecessor-version":[{"id":4686,"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=\/wp\/v2\/posts\/4683\/revisions\/4686"}],"wp:attachment":[{"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4683"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4683"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/patents.harnessip.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4683"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}