It isn't so much a myth about -ise and -ize. It is more that -ize is an old accepted variant in UK English, but has fallen out of common useage whereas it is the only form still used in the US, so while -ize in the UK may be technically accepted, it isn't socially accepted and is no longer the norm so is considered 'wrong'.
wiki says this,thoug "Sulfur comes from the Old French soufre, apparently referring from a root meaning "to burn". The element was traditionally spelled sulphur in the United Kingdom (since the 14th century), most of the Commonwealth including India, Malaysia, South Africa, and Hong Kong, along with the rest of the Caribbean and Ireland. Sulfur is used in the United States, while both spellings are used in Canada and the Philippines.
However, the IUPAC adopted the spelling sulfur in 1990, as did the Royal Society of Chemistry Nomenclature Committee in 1992. The Qualifications and Curriculum Authority for England and Wales recommended its use in 2000, and it now appears in GCSE exams. The Oxford Dictionaries note that "In chemistry... the -f- spelling is now the standard form in all related words in the field in both British and US contexts"
In Latin, the word is variously written sulpur, sulphur, and sulfur (the Oxford Latin Dictionary lists the spellings in this order). It is an original Latin name and not a Classical Greek loan, so the ph variant does not denote the Greek letter φ (phi). Sulfur in Greek is thion (θείον), whence comes the prefix thio-. The simplification of the Latin words p or ph to an f appears to have taken place towards the end of the classical period."