Complex sentence: He spent a number of years in and out of San Francisco, where he was involved with Chinese immigrants, and wrote to the "Boston Advertiser" trying to dispel public misconceptions of them as a labor force.
Split into simpler sentences: He spent a number of years in and out of San Francisco, where he was involved with the Chinese immigrants. He later wrote to the "Boston Advertiser" trying to dispel public misconceptions of them as a labor force.