During the Civil War, he was an active supporter of the Union. For many years, he gave much attention to Sunday school work and the temperance cause, and was a prominent figure in the Fulton-street prayer-meeting. Eventually, he became an ardent Spiritualist, and in 1882, was placed by some of his relatives under restraint in an insane asylum. Litigation ensued, which resulted in his release, and he gave much of his time afterwards to the investigation of cases alleged to be of a similar character, including that of Clarissa Caldwell Lathrop, who detailed her confinement in "A Secret Institution". He married, in 1856, Harriette V. C., daughter of the Rev. Alexander H. Crosby, Rector of the Episcopal Church in Yonkers, New York, where Silkman afterwards resided. In January, 1888, he had a bout of pneumonia, from which he partially recovered, but heart failure resulted in his death, at a hospital in New York City, on February 4, 1888, in his 69th year.