4337. To Coat Phosphorus with Copper

4337.    To Coat Phosphorus with Copper. Dr. Siewert, of Halle, suggests a method by which the sticks can be kept, even in the light, without undergoing deterioration. For this purpose, he takes advantage of the well-known property of phosphorus to reduce some metals from their solutions. The sticks of phosphorus are put into a cold saturated solution of the sulphate of copper. Presently they become coated with a deposit of metallic copper, and in this state resemble copper rods. They can now be removed to a bottle containing water, and will keep for years. "When a stick is wanted for any purpose, on removing the metallic film, and scraping" off a black deposit underneath it, the phosphorus will be found to have retained its translucency, as if it had been freshly cast.

4338. To Reduce Phosphorus to Powder

4338.     To Reduce Phosphorus to Powder. Melt the phosphorus in a phial containing some fresh urine, or a solution of pure urea, by the heat of hot water, and agitate until cold. Rectified spirit may be used instead of urine or urea. (See No. 1899 (Phosphorus Paste for Vermin).)

4339. Phosphorescent Oil

4339.    Phosphorescent Oil. Dissolve 1 grain phosphorus in 1 ounce olive oil in a test tube by the heat of hot water, or add a larger quantity to some oil of lavender, in which it will dissolve spontaneously. Keep in a close phial.

4340. Pyrophorus

4340.     Pyrophorus. This is a term given to substances which inflame spontaneously when exposed to the air. "When a small quantity of any of the powders given below is exposed to the air, it rapidly becomes hot and inflames. Their action is quicker in a damp atmosphere, or by the moisture of the breath.

4341. Homberg's Pyrophorus

4341.    Homberg's Pyrophorus. Stir equal parts of alum and brown sugar (or 3 parts alum and 1 part wheat flour) in an iron ladle over the fire until dry; then put it into an earthen or coated glass phial, and keep it at a red heat so long as flame is emitted; it must then be carefully stopped up and cooled.

4342. Hare's Pyrophorus

4342.   Hare's Pyrophorus. Lampblack, 3 parts; burnt alum, 4 parts; carbonate of potash, 8 parts; as above.

4343. Gay Lussac's Pyrophorus

4343.      Gay Lussac's Pyrophorus. Sulphate of potash, 9 parts; calcined lampblack, 5 parts; as last.

4344. Goebel's Pyrophorus

4344.     Goebel's Pyrophorus. Heat tartrate of lead red hot in a glass tube, and then hermetically seal it.

4345. Dextrine or Starch Gum

4345.      Dextrine or Starch Gum. Heat 4 gallons water in a water-bath to between 77° and 86° Fahr.; stir in l1/2 or 2 pounds finely ground malt; raise the temperature to 140°, add 10 pounds potato or other starch; mix all thoroughly, raise the heat to 158°, and keep it between that and 1670 for 20 or 30 minutes. When the liquor becomes thin, instantly raise the heat to the boiling point, to prevent the formation of sugar. Strain the liquor, and evaporate it to dryness, as the dextrine will not keep long in a liquid form. Another method is to boil solution of starch with a few drops of sulphuric acid, filter the solution, and add alcohol to throw down the dextrine.

Or: Mix 500 parts potato starch with 1500 parts of cold distilled water and 8 parts of pure oxalic acid; place this mixture in a suitable vessel on a water-bath, and heat until a small sample tested with iodine solution does not produce the reaction of starch. When this is found to be the case, immediately remove the vessel from the water-bath, and neutralize the liquid with pure carbonate of lime. After having been left standing for a couple of days the liquor is filtered, and the clear filtrate evaporated upon a water-bath until the mass has become quite a paste, which is removed by a spatula, and, having been made into a thin cake, is placed upon paper and further dried in a warm place; 220 parts of pure dextrine are thus obtained. (Sec No. 2925.)