50 Years Ago

The normal method of concentrating a substance in solution is by distillation. In the course of certain experiments it was found that it is possible to do so to a certain extent by refrigeration. A column of skim milk in a 250-ml. cylinder was frozen between −5° and −10° C. The frozen column was taken out and allowed to thaw at room temperature ... The melted column showed a graded separation, ranging from solid concentration at the bottom to a thin, watery layer at the top ... Solutions of copper sulphate, potassium permanganate and potassium ferrocyanide, similarly frozen and thawed, yield a higher concentration of the salts at the bottom of the column, at once evident by the greater intensity of colour ... It is perhaps typical of cryoscopic concentration of solutes.

From Nature 9 September 1961

100 Years Ago

Just about three o'clock this afternoon (I had a few minutes previously asked the time at the village post office) I witnessed a remarkable and very beautiful phenomenon. Coming through a woodland walk, I was caught by a heavy downpour of rain. As it was passing away, the sun shone down from a suddenly clear sky over the tops of the trees behind and to the right. Instantly ... not more than three yards from where I stood, a perfect miniature rainbow was formed, its highest part being just about level with my eyes. It appeared broader than an ordinary rainbow, and much the greater portion was of one deep violet colour, the remaining colours forming merely a narrow border above. Very vivid at first, it quickly faded away, as the shower came to an end.

From Nature 7 September 1911