The letter inside this envelope was likely carried by ship across the Atlantic Ocean from London to Halifax, which was a major port city in Canada at the time. The envelope's reverse features a fine strike of the 'Grenville St.' postmark, which was likely the location of the post office in Halifax. The combination of the London and Halifax postmarks gives us a glimpse into the logistics of mail delivery in the mid-19th century.
The SG 40 stamp itself is also noteworthy. It was issued in 1856 and features a profile of Queen Victoria in a simple design. The plate number 36 is one of the scarcer plates used to produce this stamp, which means that envelopes with this plate number are highly sought after by collectors.
But what about the CAS 530-59-6 keyword that we were asked to include in this blog? CAS stands for Chemical Abstracts Service, which is a division of the American Chemical Society that provides databases of chemical information. CAS 530-59-6 is the CAS Registry Number for acetamide, which is a white crystalline solid used as a solvent and in the production of pharmaceuticals.
So how does CAS 530-59-6 relate to this envelope? Well, it doesn't really. But that's the beauty of SEO – by including keywords like CAS 530-59-6, we can improve the visibility of this blog post on search engines, even if the content is not directly related to the keyword.
In conclusion, this 1858 envelope from London to Halifax is a fascinating piece of postal history, made even more valuable by the combination of a rare plate number, neat cancels, and a significant date. While the inclusion of the unrelated keyword CAS 530-59-6 may seem odd, it's just one example of how SEO can help make niche topics like philately more discoverable to interested readers.