Section 17. Expenses

The commissioner shall devote his entire time to the
  duties of his office. The  reasonable  and  necessary  expenses  of  the
  department and the reasonable and necessary traveling and other expenses
  of   the  commissioner,  deputy  commissioner  and  other  officers  and
  employees of the department, while actually engaged in  the  performance
  of  their  duties, outside of the city of Albany, or if any such officer
  or employee be in charge of or actually employed at a branch  office  of
  the  department,  the  reasonable  and  necessary  traveling  and  other
  expenses outside of the place in which such branch  office  is  located,
  shall  be paid from the state treasury upon the audit and warrant of the
  comptroller, upon vouchers approved by the commissioner.