16 denotes a nozzle numeral 17 denotes a source of pure water numeral 18 denotes particles of ice numeral 19 denotes a screw feeder numeral 20 denotes a hopper and numeral 21 denotes a blast device for example the container 11 which is 400 u00d7 400 mm 2 in cross section and 1200 mm in height is filled up to 500 mm in height with the liquid nitrogen 13 supplied from the source of liquid nitrogen 12 the liquid nitrogen ln 2 13 generates a wave having wavelength of several mms on the surface thereof by flowing nitrogen gas gn 2 from the diffuser 14 at the rate of 300 l min this nitrogen gas is supplied through the heat exchanger 15 from the source of liquid nitrogen 12 on the other hand the nozzle 16 provided on the top of the container 11 is supplied with pure water from the source of pure water 17 at the pressure of 1 2 kg cm 2 g and at the flow rate of 0 1 l min while the nitrogen gas is supplied at the pressure of 1 2 kg cm 2 g and at the flow rate of 4 5 nl min then the pure water is sprayed in a fog manner from the nozzle 16 thus the pure water sprayed in a fog manner into the liquid nitrogen 3 changes into fine particles of ice 18 instantly the particles of ice at the level of about 70 to 80 u03bcm are obtained under the spraying condition as described above and the diameters of these fine particles of ice can be controlled variously by adjusting the spraying condition of pure water stay time in the liquid nitrogen and the like the particles of ice 18.