Water at `0^@C` was heated until it started to boil and then until it all changed to steam. The time required to heat water from `0^@C` to `100^@C` is 5 min and the time to change boiling water to steam is 28 minutes. If the flame supplied heat at a constant rate, the specific latent heat of vaporisation of water (neglecting heat losses, container etc. is (in `J//g`). (specific heat of water s `=4.2 J//g` )