Galvanic corrosion is a process that degrades metals electrochemically. This corrosion occurs when two dissimilar metals are located in contact with each other in the presence of an electrolyte, such as salt water, forming a galvanic cell.
But the memories of that tragic day 25 years ago are still vivid to many in Edmond. On Aug. 20, 1986, gunman Patrick Henry Sherrill shot and killed 14 co-workers, wounded six and then took his own life inside the post office where he worked.
Seal of the former U.S. Post Office Department (1792â1971), predecessor to the USPS. Initial United States postage rates were set by Congress as part of the Postal Service Act signed into law by President on February 20, 1892. The postal rate varied according to distance zone, the distance a letter was to be carried from the post office where it entered the mail to its final destination.