In Portrait of Jacob Wiemer, Gustave Vanaise captures a seated figure, Jacob Wiemer, dressed in formal attire. The color palette consists of muted earth tones, with soft highlights that illuminate Wiemer's face. The background is a simple, dark hue that emphasizes the subject.

The overall composition conveys a sense of dignity and introspection. The painting is executed in oil on canvas, a common medium for portraits of this period. Vanaise employs a realistic style, focusing on the intricate details of Wiemer's clothing and facial features. The brushwork is smooth, allowing for a lifelike representation of the subject.

The dimensions are approximately 60 x 80 cm, making it a moderately sized portrait. Gustave Vanaise was known for his portraits that often depicted individuals in a realistic manner. This particular work, created in the late 19th century, reflects the growing interest in capturing the essence of individual subjects. An interesting fact about this painting is that it was commissioned by Wiemer's family, highlighting the personal connection and significance of the artwork.