820 
been shown recently that the saving in excess 
of soap consumed by a hard water will render 
it economical for a city to expend a consider- 
able sum in softening a hard water supply. In 
a recent number of the Journal of the American 
Chemical Society, M. L. Griffin gives the details 
of a series of experiments in the use of several 
softening agents. Waters containing less than 
.025 grams lime and .007 grams magnesia can- 
not be appreciably purified, though harder 
waters can often be reduced below these figures 
by purification. Calcium carbonate is most 
effectively removed by sodium hydroxid, sodium 
fluorid, and in some cases sodium aluminate. 
Calcium sulfate and chlorid are best treated with 
sodium fluorid, which, however, has no effect 
on magnesium salts. Sodium hydroxid is the 
most useful reagent for magnesium salts, and 
barium hydroxid follows, but the latter is not 
satisfactory for waters containing a large pro- 
portion of calcium carbonate and sulfate. 
In the Journal of the Russian Chemical So- 
ciety a new cerium mineral from the Caucasus 
is described by G. Tschernik, which from the 
analysis seems to be essentially a titanate and 
zirconate of cerium. It contains a gas which is 
90% a mixture of nitrogen and argon. The 
mineral contains but .03% uranium and no 
helium. The ash of a coal from Tkwibuli, 
which was chiefly calcium sulfate, with alumina 
and silica, and about 10% of ceria, lanthana 
and didymia, showed the presence of over 1% 
of helium. 
THE Report of the Australian Association for 
the Advancement of Science contains a descrip- 
tion by Thomas Steel of a ‘red rain’ which fell 
over Melbourne and much of Victoria on De- 
cember 27, 1896. The rain carried down an 
unusually heavy fall of dust of red color, which 
appeared on analysis to be an ordinary surface 
soil derived from volcanicrocks. Under the 
microscope the presence of diatoms, scales of 
lepidoptera, quartz and garnet were detected. 
AN instance of the use of liquid ammonia as 
a solvent is shown by C. Hugot in the Comptes 
Rendus, where the selenids of sodium and 
potassium are thus formed. A mixture of 
selenium with the alkali metal is treated with 
liquid ammonia. If the metal is in excess the 
SCIENCE. 
[N. S. Von. X. No. 257, 
insoluble selenid Na,Se or K,Se is formed while 
if the selenium predominates a polyselenid Na, 
Se, or K,Se, is formed, which is dissolved in 
the ammonia and is obtained on its evaporation. 
Contrary to the observation of Franklin and 
Krauss, Hugot finds that selenium itself is in- 
soluble in liquid ammonia. J. L. H. 
TECHNICAL UNIVERSITY DEGREES. 
A LETTER, recently received from Ex-Presi- 
dent Andrew D. White, our Minister to Berlin, 
relative to matters educational, mainly, tells of 
the festival on the 100th anniversary of the 
founding of the great technical college at Char- 
lottenburg, Berlin. This celebration, with its 
processions, its speech-making by the Emperor 
and other notables, and the structure and dec- 
orations of the great college buildings, have 
been fully described by press correspondents ; 
but it has not been stated, so far as has been 
observed, except in a brief note in ScrENCE, 
that the Emperor, while erecting this splen- 
did institution into a national, technical, uni- 
versity, making its powers those of the aca- 
demic universities and its director a ‘ Rector 
Magnificus,’ conferred also the special power of 
giving the degree ‘ Dr. Ing.,’ doctor of engineer- 
ing, a degree already established in this country, 
in 1884, at the initiative of the writer, and very 
sparingly conferred, to date, by the Stevens 
Institute of Technology. 
The event, both as being the occasion of the 
formal institution of a national technical uni- 
versity, and as giving formal and official recog- 
nition to a degree which gives claim to full 
standing of the profession of Archimedes and 
Leonardo and the Marquis of Worcester, beside 
those of Hippocrates and of Justinian, was one 
of unusual importance and significance. This 
movement has been a vitally important part of 
that systematic programme which has led to the 
industrial triumph of Germany, of which Dr. 
White says in thisletter: ‘‘ It is amazing to see 
how, in their way, the Germans have gone 
steadily on until they have established a won- 
derful system of manufacturers all over their 
country and an astonishing commercial connec- 
tion, through fleets of great steamers going to 
all parts of the world.”’ 
R. H. THURSTON. 
