384 
POPULAR SCIENCE REVIEW. 
consent to throw away their present knowledge and go to school again, such 
concentrated essence of language might be useful, but under existing cir- 
cumstances its partial adoption would be injurious rather than beneficial. 
The phenomena of phosphorescence are well known to accompany many 
chemical changes. These have recently been studied by Reichenbach, who 
shows that phosphorescence, or the continuous emission of light in dark- 
ness, is a much more common occurrence than it is usually supposed to 
be. Thus there is phosphorescence during fermentation or putrefaction, 
crystallization, evapoi’ation, condensation of vapours, the production of 
sound and the fusion of ice ; a considerable glow is remarked when a 
galvanic pile in activity, a block of ice undergoing fusion, or a solution of 
sulphate of soda in the act of crystallizing, are observed in the dark. The 
human body itself is not devoid of phosphorescence ; in a healthy state it 
emits a yellow glow, whilst in ill health the colour of the light assumes a 
reddish tinge. To perceive these phenomena, the eye ought to have been 
previously rendered sensitive by remaining for some hours in perfect dark- 
ness, and even then all eyes are not equally impressionable : if, however, 
several persons unite in performing the experiment together, there will 
always be a certain number who are able to perceive the phenomena. 
Those of our readers who remember the strange announcement made by 
Reichenbach some years ago, of the existence of a new force in nature, 
which lie termed the odylic force, and have not forgotten the incredulity 
with which his statements were received, will be disposed to accept any 
similar observations cum grano salis. It must not, however, be forgotten 
that the propounder of these strange theories is one of the first chemists 
and physicists of the day, and his researches in this “occult” science are 
characterized by equal philosophical acumen with his chemical experi- 
ments. 
The new alkali metals, the discovery of which by Bunsen, by means of 
“ spectrum ” observations, we noticed in our last number, have been proved 
by L. Grandean to be more commonly diffused than was at first imagined. 
They have been found in Vichy water, in the thermal waters of Bourbonneles 
Bains, and in many specimens of lepidolite. From the residues obtained 
in working 100 kilogrammes of this mineral, together with petalite and 
iriphylline, for the alkali lithia, M. Grandean has prepared considerable 
quantities of the new alkalies, rubidia, and cassia. They have likewise been 
detected in about equal proportions in some residues of the manufacture of 
saltpetre on a Paris refinery. In similar residues from Belgium saltpetre 
much rubidia, but no csesia has been found. Chili nitrate of soda has not, 
however, been found to yield anything but soda and traces of potash. 
Wittstein has verified Tyndall’s observation that pure water is not 
colourless but blue. He has also established that the mineral matters 
which a water may contain do not affect the colour, but that the variety of 
tints, observed in different masses of water, are due to the presence of 
organic matter, held in solution by an alkali. He also finds that it may 
be universally accepted as a rule, that the browner a natural water 
the softer it is, and that it becomes harder as its colour approaches a 
pure blue. 
A curious action of silicic acid has been noticed by J. C. Leuchs. He 
