| OCR Text |
Show - 5- Sample with I~ heptaldehydes The physical appearance of this sample was obviously different from the others throughout the experiment « While all other samples settled from a thickness of 6 cm to about 2.5 cm, this one settled to a final thickness of 3.5 cm. Sample surface under the black disk was dense and white, in contrast to the more porous and slightly grey appearance of the others. Recrystallization was very markedly inhibited, the sublimations forms being reduced to about 25$ of the total speciment, all well under 1 mm in size. Upper half of the speciment was noticeably firmer than in the others, while at the bottom, the structure was still soft and similar to the original fresh snow, although the crystals no longer retained their identity. Crystal type was mostly cups, and the general appearance similar to the initial stages of natural depth hoar formation. Sample with dibenzyl amines This sample resembled that with the N- heptaldehyde, but depth hoar inhibition was less marked. Crystals were mostly normal cups and scrolls, around 1 mm in size. Texture was soft, rather than fragile. Conclusions These initial tests are sufficient only to point the way to further experiment. Refinement of the laboratory technique is needed, using larger samples which are physically separated to minimize the diffusion of organic vapors from one sample to another, which must be considered a possibility in this first experiment in spite of attempts to seal the samples* A wide variety of chemicals need to be tested in the laboratory in order to isolate those most promising for field tests. The actual effects on mechanical stability need to be determined in |
