the letter "j" is now often included in the alphabet, between "i" and "l", due to its use in several loanwords from english (especially the common surname "jones" ). the letters "k", "v", "x" and "z" are used in some technical terms, like "kilogram" , "volt" , "xeroser" and "zero" , but in all cases can be, and often are, replaced by welsh letters: "cilogram" , "folt" , "seroser" and "sero." the letter "k" was in common use until the 16th century, but was dropped at the time of the publication of the new testament in welsh, william salesbury responding to critics: "c for k, because the printers have not so many as the welsh requireth". this change was not popular at the time