To the Editor of the NorrH-Cuina Dany News."
Sim—In reply to "Henry's" inquiry'in your issue of the 28h as to why air saturated with water vapour is lighter than dry air, the fundamental reason is that the molecule of water freight less than the molecule of oxygen or nitrogen, being 18 protons as against 32 and 28. In saturated wit there is just enough water vapour to balance the fa poration from a water surface and this fraction (depending on temperature) of the atmosphere consists of the lighter water-gas so that the average density is less. Tam, ete,
Text read from the printed page and cleaned; old type leaves the occasional error.