Dear all !
I don't know about 18' th or 19' th Century...all I know is that we are in 21'
st century....communication is must no matter if it is ise or ize....I personally use ize ..It hardly matter if I am interacting with UK client or US..Eg. If I write optimization while communicating with some UK person ...then of course he will know what I mean...and if I write optimisation to my US client he will also know what I am talking about ...as far as spelling check is concerned I think every one know how to change language of laptop or any electronic media .....just change language from UK English to US English and see the difference..