Abstract: The present invention achieves energy saving and a decrease in facility cost for a hot water supply device by dividing a water receiving tank. A hot water supply system comprising: a water receiving tank receiving water supplied from a water supply source; a hot water storage tank connected to the water receiving tank via a connection pipe and storing hot water and supplying hot water to a hot water supply load; and a hot water supply device supplying the water stored in the hot water storage tank.

Abstract: The present invention achieves energy saving and a decrease in facility cost for a hot water supply device by dividing a water receiving tank. A hot water supply system comprising: a water receiving tank receiving water supplied from a water supply source; a hot water storage tank connected to the water receiving tank via a connection pipe and storing hot water and supplying hot water to a hot water supply load; and a hot water supply device supplying the water stored in the hot water storage tank.

Abstract: A polyurethane lens is produced by (a) adding to a monomer mixture comprising a polyisocyanate and a polythiol, a phosphoric acid ester represented by the general formula (I) ##STR1## (R.sub.1 and R.sub.2 which may be the same or different are each an alkyl group of 1-8 carbon atoms) and then (b) subjecting the monomer mixture containing the phosphoric acid ester, obtained in the step (a) to cast polymerization in a mold for plastic lens production. Said polyurethane lens has good releasability from mold, is free from color unevenness after tinting and cloudiness, and possesses high refractive index (N.sub.D) and high optical dispersion.

Abstract: A lens having a high refractive index with a low dispersion produced by copolymerizing a polyfunctional allyl monomer with at least one monomer selected from the group represented by the general formula A: ##STR1## X: H, CH.sub.3, Cl Y: H, CH.sub.3, C.sub.2 H.sub.5, n-C.sub.3 H.sub.7, iso-C.sub.3 H.sub.7, OCH.sub.3, C.sub.6 H.sub.11, Cl, Br, CH.sub.2 Cl, CH.sub.2 Br, C.sub.6 H.sub.5, CH.sub.2 C.sub.6 H.sub.5, SCH.sub.3m=0, 1, 2n=0, 1, 2, 3, 4, 5.This lens is excellent in its transmittance, pencil hardness, impact resistance, dyeability, coating adhesion, solvent resistance, workability, etc.

Abstract: A high refractive lens of a terpolymer produced by the polymerization of ternary monomers comprising diethylene glycol bisallyl carbonate, triallylisocyanurate, and benzyl methacrylate. This lens is considerably improved in its physical properties necessary for lens such as superficial hardness, transmittance, and adhesion strength of glass film coated on the surface, as well as having a high refractive index.