thereafter dehydrated under vacuum and when the temperature of the resin in the vessel reached 170 u00b0 c the resin was taken out of the vessel thus 950 parts of a novolac type phenolic resin which was solid at ordinary temperature were obtained 1 000 parts of phenol and 650 parts of 37 formalin were charged into a reaction vessel equipped with a reflux condenser and a stirrer and then 10 parts of oxalic acid were added thereto the temperature was gradually raised and when it reached 96 u00b0 c the mixture was refluxed for 90 minutes the mixture was thereafter dehydrated under vacuum and when the temperature of the resin in the vessel reached 170 u00b0 c the conversion for formaldehyde in the formalin was 99 and the water content in the system was 0 4 5 parts of ammonium chloride was added to the reaction mixture and they were mixed for 15 minutes the reaction mixture was taken out of the vessel thus 955 parts of a novolac type phenolic resin which was solid at ordinary temperature were obtained 1 000 parts of phenol and 650 parts of 37 formalin were charged into a reaction vessel equipped with a reflux condenser and a stirrer and then 10 parts of zinc acetate was added thereto the temperature was gradually raised and when it reached 90 u00b0 c the mixture was refluxed for 240 minutes the mixture was thereafter dehydrated under vacuum until the temperature of the mixture.