The mayor of Providence, David N. Cicilline, has been floating ideas for weeks on how to get tax revenue out of private colleges -- alarming many of them in the process. On Wednesday, he formally unveiled his proposals, which will be considered by Rhode Island lawmakers, The Providence Journal reported. One bill would allow local governments to tax private colleges $150 for every full-time student enrolled from out of the state. The other bill would subject private colleges to local property taxes of up to 25 percent of what entities that are not tax-exempt would pay.