[3] He developed his alleged paranormal abilities of automatic writing, clairvoyance and psychometry in the 1920s after his son died in a plane crash.

[4][5] He was tested by psychical researchers such as Eugéne Osty and Charles Richet who were convinced he had genuine paranormal powers.

During an anonymous sitting in 1929, Forthuny had pretended to obtain his name by automatic writing but it was discovered that he previously attended lunch with psychical researchers Eleanor Sidgwick and V. J. Woolley who told him the afternoon sitter was Soal.

[9] This type of experiment was originally devised by Eugéne Osty at the Institut Métapsychique International and conducted with Forthuny in April 1926.

Criticism of the chair tests came from Antônio da Silva Mello who found the results suspicious as they were never replicated.