Note 74 bis — Chapter XX · SULPHUR, SELENIUM, AND TELLURIUM

Thorpe and Rodger (1889), by heating a mixture of lead fluoride and phosphorus pentasulphide to 250° in an atmosphere of dry nitrogen, obtained gaseous phosphorus fluosulphide, or thiophosphoryl fluoride, PSF3, corresponding with POCl3. This colourless gas is converted into a colourless liquid by a pressure of eleven atmospheres; it does not act on dry mercury, and takes fire spontaneously in air or oxygen, forming phosphorus pentafluoride, phosphoric anhydride, and sulphurous anhydride. It is soluble in ether, but is decomposed by water: PSF3 + 4H2O = H2S + H3PO4 + 3HF (Note 20).