In what environment were the Momblan Peak and glaciers, the highest peaks in the Alps, photographed?

This photo was taken at 1860. At that time, in order to carry heavy photographic equipment, the Bassong brothers hired 25 porters. In bad weather conditions, they struggled to climb for three days and nights before reaching the top of the mountain. In order to develop the photos, the Basong brothers melted the snow with kerosene lamps. But because of the high altitude and thin air, even kerosene lamps are not easy to burn. The Bassong brothers took three negatives, and when they came back, people set off sparks and salutes to greet them.