During the reconstruction of the palace, Alexander Sergeyevich Stroganov commissioned an alchemical laboratory for himself, which is now modestly called the Physical Cabinet. Here is how a contemporary described the cabinet: Upon entering the cabinet, the visitor found themselves in a peculiar "alley of sphinxes," consisting of cabinets with books and tables with busts of philosophers, globes, armillary spheres, and a telescope, forming a narrow passage. Proceeding further, the visitor stood between two columns with lotus-shaped capitals, framing the entrance to the laboratory itself. In the middle of the vaulted room was the most important feature—the alchemical furnace. Four "bronze mummies," i.e., four male and four female figures of Egyptian appearance, supported the hood above the furnace, a reflector that reflected the heat. Firewood was placed in the fireplace, and the crucibles, which needed to be heated, were located in the central part, the "athanor," covered with crystal discs that allowed observation of the processes inside the vessels. The walls and beams of the hall were decorated with pseudo-hieroglyphs and an image of a flying solar disk (fragments of which have been preserved). Along the walls stood cabinets containing certain "antiquities," and between them was a secret door. Against the wall stood a granite herm of Jupiter-Ammon, made by Samson Sukhanov in 1810.

Herms are four-sided pillars topped with a sculpted head originally of the god Hermes (hence the name), which in ancient times served as boundary markers and road signs. "Many art lovers know the beautiful granite bust made by Sukhanov for the late Count Alexander Sergeyevich Stroganov," wrote the Russian writer Svinin in the "Domestic Notes" in 1818. Mineralogist Zembnitsky gave the first detailed description of the sculpture. He wrote, in particular: "At first glance at this bust, one is amazed, thinking they see before them a work of ancient art, but this amazement grows even more when reading the inscription on its pedestal, expressed in the following words: Ars aegyptiaca Petropoli renata MDCCCX, that is: Egyptian Art renewed in Saint Petersburg in 1810."

The bust of the Egyptian "king of the gods" Ammon was made after a copy of Zeus from Otricoli of the 4th century BC. The pedestal of the herm is composite. Its upper main part, carved from red Finnish granite in the form of a straight quadrangular prism, is set on a low pedestal made of gray Serdobol granite.

The pedestal of the herm turned out to be so heavy that it still stands in its original place. Its proportions, in a ratio of 1:10, correspond to the proportions of the Physical Cabinet itself, and in a ratio of 1:50—to the proportions of the nave of the Kazan Cathedral, which was visible from the window of the alchemical laboratory. It is precisely against the background of this window in the Physical Cabinet that the owner is depicted in the famous portrait.

Doctor of Historical Sciences, Professor Kuznetsov, in the book "Stroganov Palace," suggested that besides the alchemical laboratory, a Masonic lodge gathered in this cabinet. There was a Masonic sanctuary and the Commission for the Construction of the Kazan Cathedral met there. There is reason to believe that it was through this statue that a mystical connection was established for the "freemason" Stroganov between his home and the Kazan Cathedral, which he was building. Alexander Sergeyevich held high positions in Masonic lodges in Prussia and France and was a member of the famous lodge "Les Neuf Sœurs." He participated in the creation of the Masonic organization called the Grand Orient of France and held several administrative positions there.

Sources:

https://ru.wikipedia.org/wiki/Строганов,_Александр_Сергеевич

http://edu.hermitage.ru/catalogs/1424282991/fact/1424348413