Scientific amusements . ur giving a phos-phorescent light of very pure violet. Carbonate of limeobtained by forming a precipitate of crystallized chlorideof calcium with different alkaline carbonates also givessatisfactory results. Luminous sulphates of strontium may be obtained, likethose of calcium, by the action of sulphur on strontia orthe carbonate of this base, by the reduction of sulphatesof strontia with charcoal. Blue and green shades are themost common. Sulphates of barium also present veryremarkable phenomena of phosphorescence ; but to obtainvery luminous intensity a higher tempera
Scientific amusements . ur giving a phos-phorescent light of very pure violet. Carbonate of limeobtained by forming a precipitate of crystallized chlorideof calcium with different alkaline carbonates also givessatisfactory results. Luminous sulphates of strontium may be obtained, likethose of calcium, by the action of sulphur on strontia orthe carbonate of this base, by the reduction of sulphatesof strontia with charcoal. Blue and green shades are themost common. Sulphates of barium also present veryremarkable phenomena of phosphorescence ; but to obtainvery luminous intensity a higher temperature is needed* These substances must be finely powdered and thoroughly mixed. 42 CHEMISTRY. than with the other substances mentioned, and we have thesame result when we reduce native sulphate of baryta withcharcoal; that is to say, when the reaction takes placewhich produces the phosphorus formerly known as phos-phorus of Bologna. Preparations obtained from barytahave a phosphorescence varying from orange-red to Phosphorescent flower emitting hght in a daric rooui. The preparation of such substances as we have justenumerated afford an easy explanation of the method ofmanufacturing the luminous flowers which we describdd LUMINOUS fLOWEllS. 43 at the commencement of this chapter. We obtain someartificial flowers, cover them with some liquid gum, sprinklewith phosphorescent sulphur, and let them dry. The pul-verulent matter then adheres to them securely, and it isonly necessary to expose the flowers thus prepared to thelight of the sun, or the rays emanating from magnesiumwire in a state of combustion (page 39), to produce im-mediate phosphorescent effects. If taken into a dark roompage 42) they shine with great brilliancy, and give off veryexquisite coloured rays. Phosphorescent sulphates are usedalso in tracing names or designs on a paper surface, etc.,and it can easily be conceived that such experiments maybe infinitely varied according to the pleasure of the ex-perime
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