Deformable bag for use as cooling medium

A deformable bag for use as a cooling medium which comprises:

• (a) A flexible envelope, and
• (b) A plurality of small pieces of a polyvinyl alcohol gel having a high water content packed within said envelope, said gel having been prepared by the steps of forming an aqueous solution or suspension of a mixture of a water-soluble organic compound and a polyvinyl alcohol having a degree of hydrolysis of not less than 95 mol % and an average polymerization degree of not less than 1,100, the concentration of said organic compound in said mixture being adjusted to be in the range of from 5 to 40 wt % and the concentration of said polyvinyl alcohol in said mixture being more than 8 wt % and not more than 25 wt %, casting said aqueous solution or suspension into a mold having the desired shape and dimensions, cooling the cast aqueous solution or suspension to a temperature of not higher than -(minus) 10.degree. C. to solidify the same to form a molded mass of solidified gel, and then partially dehydrating, without thawing, the molded mass of solidified gel in vacuum until the percentage dehydration rate (the weight reduction rate of the solidified gel) reaches not less than 3 wt %.