OCR Text |
Show - 3- Sample with N- heptaldehyde; Fine- grained, moderately firm crystals without fragility developed in about 25$ of the sample. All crystals were under 1 mm and tended to form plates. Sample with N- heptaldehyde ( one drop only in center of sample); The sample center was moderately firm and showed little fragility, but the snow was fragile around the edges. The center was recrystallized to 75$ depth hoar, and the edges to 90$, both with crystals around 1- 2 mm in size. Control samples: Both of these were moderately fragile, showing some slight firmness, and were 80- 90^ recrystallized to rather fine- grained depth hoar 1- 3 mm in size. One sample showed a slight tendency to form squared corners on the crystals, while the other had a few long needles. In this test the inhibiting effects of N- heptaldehyde found in the first test were duplicated, and benzaldehyde was found to be an even more effective depth hoar inhibitor. Ethylene glycol also fell into this category, though not quite as effective as the aldehydes. Because the latter is cheap, readily available and not objectionable to handle, it probably will prove the best agent for any extensive field tests of depth hoar inhibition. The aldehydes are highly aromatic, and N- heptaldehyde in particular is very objectionable and toxic, so these do not appear suitable for practical field use. Field Tests at Berthoud Pass Following completion of the first experiment in the deep freeze unit at Alta, a small- scale pilot test in the field was started at Berthoud |