Floods also occasionally do considerable damage. The bushes are attacked at intervals and in patches by a blight similar to that which injures the vines of the country.
The bushes are planted in hedge-like rows in gardens and fields, at convenient distances apart, for the gathering of the crop. They are seldom manured. The planting takes place in spring and autumn ; the flowers attain perfeetion in April-May, and the harvest lasts from May till the beginning of June. The expanded flowers are gathered before sunrise, often with the calyx attached ; such as are not required for immediate distillation are spread out in cellars, but all are treated within the day on which they are plucked. Baur states that, if the buds develop slowly, by reason of cool damp weather, and are not much exposed to sun-heat when about to be collected, a rich yield of atto having a low solidifying-point, is the result ; whereas, should the sky be clear and the temperature high at or shortly before the time of gathering, the product is diminished, and is more easily congealable. Hanbury, on the contrary, when distilling roses in London, noticed that, when they had been collected on fine dry days, the rose-water had most volatile oil floating upon it, and that, when gathered in cool rainy weather, little or no volatile oil separated.
The flowers are not salted, nor subjected to any other treatment, before being conveyed in baskets, on the heads of men and women, and backs of animals, to the distilling apparatus. This consists of a tinned-copper still, erected on a semicircle of bricks, and heatod by a wood fire ; from the top, passes a straight tin pipe, which obliquely traverses a tub kept constantly filled with cold water, by a spout from some convenient rivulet, and constitutes the condenser. Several such stills are usually placed together, often beneath the shade of a large tree. The still is charged with 25-50 lb. of roses, not previously deprived of their calyces, and double the volume of spring water. The distillation is carried on for about lf hour, the result being simply a very oily rose-water (gItyul-sugu). The exhausted flowers are removed from the still, and the decoction is used for the next distillation, instead of fresh water. The first distillates from each apparatus are mixed and
distilled by themselves, one-sixth being drawn off ; the residue replaces spring water for subsequent operations. The distillate is received in long-necked bottles, holding about 11 gal. It is kept in them for a day or two, at a temperature exceeding 15° (59° F.), by which time, most of the oil, fluid and bright, will have reached the surface. It is skimmed off by a small, long-handled, fine orificed tin funnel, and is then ready for sale. The last-run rose-water is extremely fragrant, and is much prized locally for culinary and medicinal purposes. The quantity and quality of the otto are much influenced by the character of the water used in distilling. When hard spring water is employed, the otto is rich in atearoptene, but less transparent and fragrant. The average quantity of the product is estimated by Baur at per cent. ; another authority says that 3200 kilo. of roses give 1 kilo. of oil.
Pure otto, carefully distilled, is at first colourless, but speedily becomes yellowish ; its sp. gr. is at 22e F.); its boiling-point is 229° (444° F.) ; it solidifies at 11°-16° (52°-61° F.), or still higher ; it is soluble in absolute alcohol, and in acetic acid. The most usual and reliable tests of the quality of an otto are (1) its odour, (2) its congealing-point, (3) its crystallization. The odour can be judged only after long experience. A good oil should congeal well in five minutes at a temperature of 12I,P (54° F.); fraudulent additions lower the congealing-point. The crystals of rose-stearoptene are light, feathery, shining plates, filling the whole liquid. Almost the only material used for artificially heightening the apparent proportion of stearoptene is said to be spermaceti, which is easily recognizable from its liability to settle down in a solid cake, and from its melting at 50° (122° F.)., whereas stearoptene fuses at 33° (91i F°.). Possibly paraffin-wax (see Paraffin) would more easily escape detection.