Fig. 156.
a. The flask containing the phosphide of calcium and water, and placed in a water-bath heated to 140° Fah. b. Bent tube conveying the gas to c c, the U-shaped tube, to which it is attached by india-rubber tubing, c c. The U-shaped tube, surrounded with a freezing mixture. d d. Bent tube, passing into a cup of water to prevent contact with air.
Ninth Experiment.
Phosphide of calcium is quickly prepared by placing some small pieces of lime in a crucible and making them red-hot; if lumps of dry phosphorus are thrown into the crucible, and the cover placed on quickly, and immediately after the phosphorus, the latter unites with the calcium, and forms a brown substance which produces gaseous phosphide of hydrogen (PH3) when placed in water, and the gas takes fire spontaneously when it comes in contact with the air.
Tenth Experiment.
Phosphorus placed in a retort with a tolerably strong solution of potash, and a small quantity of ether, affords a large quantity of phosphide of hydrogen (commonly called phosphuretted hydrogen) when boiled. The neck of the retort must dip into a basin of water, and the object of the ether is to prevent the combustion of the first bubbles of gas inside the retort, which by their explosion would probably break the glass. If the neck of the retort is kept under water in which potash is dissolved, the gas may be generated for many days at pleasure, although it is not a desirable experiment to renew too often, on account of the disagreeable odour produced. (Fig. 157.)
Fig. 157.
A retort containing the phosphorus, water, potash, and ether. b. Neck dipping into a basin of water. c. The gas burning, and producing beautiful rings of smoke.