(5 ILCS 255/6)
(from Ch. 101, par. 6)
When any oath authorized or required by law to be made is made out
of the state, it may be administered by any officer authorized by the laws
of the state in which it is so administered, and if such officer have a
seal, his certificate under his official seal shall be received as prima
facie evidence without further proof of his authority to administer oaths.
(Source: R.S. 1874, p. 725