chemistry teacher

 There was a three teacher one is physician,another is zoologist and chemist.once in a holiday they went to visit ranipokhari then     phisician teacher said i have to measure the density of water and he jumped in the water long time was spend he doesn't  come then the zoologist said that perhaps the fish has eaten him i will do surgery and he also jumped into the water he was also  dissappear in the pond then at last the chemist teacher wrote the theory that'the physician and the zoologist both are highly soluble in water'.