Leiter Hospital 1898, medical degree records for Goslau

Justus Goslau is said to have been a doctor at Leiter Hospital in 1898. He was only 21 so I wonder if this is true? His record of enlistment in the Hospital Corps is dated May, 1898 and then discharged later that year.

He is said to have been a druggist and later a chemist for the city of Newark NJ. How might I find a record of his medical degree?