Juillerat was a friend of Sargent in Paris. He was born in 1856. He was a French lithographer and sculptor who studied at the artier of Carolus-Duran with Sargent. 

He received a third class medal at the Salon in 1895, a second class in 1899, and a silver medal at the Exposition Universelle in 1900. He was created Chevalier of the Légion d'Honneur  in 1909. [1] 

Note: 

Sold Sotheby's; 5/25/1988; Lot 190; $231,000 

Date by Charles Merrill Mount list. Ormond and Kilmurray think possibly it could have even been 1887. 

(1) 
(Ormond, Richard; and Kilmurray, Elaine; John Singer Sargent, The Early Portraits, Complete Paintings Vol I.) 
 

• See the year in review 1878