An active modification of nitrogen, produced by the electric discharge.—V

Experience has led to certain modifications of detail in preparing nitrogen for the experiments. Commercial nitrogen from cylinders is still used, but instead of passing it over phosphorus it is allowed to stand in contact with it for some hours. The former method does well enough when the phosphorus is freshly cut, but in time the surface deteriorates, owing, in part at least, to the accumulation of oxides of phosphorus, which tend to obstruct access of the gas. Two 15-litre aspirator bottles are arranged as a gasholder in the usual way, the gas being displaced by water. In the gas space is hung up a muslin bag containing chopped phosphorus. On filling the gasholder with commercial nitrogen the phosphorus fumes freely, and all traces of oxygen are removed in the course of two or three hours. The fumes subside, and the gas is ready for use. It merely requires drying on its way to the discharge tube. This 15-litre supply is more than enough for most experiments. When it is used up the water rises and drowns the bag of phosphorus, dissolving out the oxides which have been formed, and leaving it in good condition for use next time.