The clouds were very grand--grander indeed than anything I had ever before seen. Some of them seemed to hold thunder in their breasts, they were so dense and dark; others, with their faces turned sunward, shone with the dazzling whiteness of the mountain snow; while others again built themselves into forms resembling gigantic elm trees, loaded with foliage. Towards the horizon the luxury of colour added itself to the magnificent alternations of light and shade. Clear spaces of amber and ethereal green embraced the red and purple cumuli, and seemed to form the cradle in which they swung. Closer at hand squally mists, suddenly engendered, were driven hither and thither by local winds; while the clouds at a distance lay "like angels sleeping on the wing," with scarcely visible motion. Mingling with the clouds, and sometimes rising above them, were the highest mountain heads, and as our eyes wandered from peak to peak, onwards to the remote horizon, space itself seemed more vast from the manner in which the objects which it held were distributed. [Sidenote: INTENSITY OF SOUND. 1857.] I wished to repeat the remarkable experiment of De Saussure upon sound, and for this purpose had requested Simond to bring a pistol from Chamouni; but in the multitude of his cares he forgot it, and in lieu of it my host at the Montanvert had placed in two tin tubes, of the same size and shape, the same amount of gunpowder, securely closing the tubes afterwards, and furnishing each of them with a small lateral aperture. We now planted one of them upon the snow, and bringing a strip of amadou into communication with the touchhole, ignited its most distant end: it failed; we tried again, and were successful, the explosion tearing asunder the little case which contained the powder. The sound was certainly not so great as I should have expected from an equal quantity of powder at the sea level.[B] The snow upon the summit was indurated, but of an exceedingly fine grain, and the beautiful effect already referred to as noticed upon the Stelvio was strikingly manifest. The hole made by driving the baton into the snow was filled with a delicate blue light; and, by management, its complementary pinky yellow could also be produced. Even the iron spike at the end of the baton made a hole sufficiently deep to exhibit the blue colour, which certainly depends on the size and arrangement of the snow crystals. The firmament above us was without a cloud, and of a darkness almost equal to that which surrounded the moon at 2 A.M. Still, though the sun was shining, a breeze, whose tooth had been sharpened by its passage over the snow-fields, searched us through and through. The day was also waning, and, urged by the warnings of our ever prudent guide, we at length began the descent. [Sidenote: AN UNEXPECTED GLISSADE. 1857.]