Avaust 11, 1899. ] 
the observer ten feet or more from the screen 
there is no inferiority in the sensation he re- 
ceives. In the case of ordinary stereoscopic 
views the reality is lessened by the small size ; 
an ordinary view looks like a view into a model, 
but a view in life-size isa real matter. Curi- 
ously enough, a view larger than life-size is 
singularly impressive and fascinating. 
The advantage is surely very great in getting 
a whole museum of statues or of natural history 
specimens, in keeping the collection in a single 
ease, and in being able to show them at any 
moment by merely turning on the switches or 
stop-cocks of a double lantern. 
E. W. SCRIPTURE. 
PSYCHOLOGICAL LABORATORY, 
YALE UNIVERSITY, NEW HAVEN, Conn. 
POT-HOLE VS. REMOLINO. 
To THE EDITOR OF SCIENCE: Something 
more than formal advocacy of a word is usually 
necessary for its adoption ; it must survive by 
its own fitness. In so far, however, as indi- 
vidual recommendations may have weight I 
may say thatI am in favor of Mr. O. H. Her- 
shey’s suggestion that the word remolino be 
used in place of pot-hole. 
The objections to the use of the word remo- 
lino raised by Mr. F. F. Hilder in ScrENcE of 
July 21st do not seem to me to be well founded. 
Is it true that ‘‘the term pot-hole expresses the 
object to which it is applied more correctly than 
the Spanish word ?’’? While the term may have 
been applied on account of the shape of the 
holes, it is more likely that it gained its use 
from a common belief that the holes were ex- 
cavated by the Indians for cooking purposes. 
If this be the case the word pot-hole is more 
misleading than remolino, for the latter, at least, 
gives a correct suggestion as to the way in 
which the holes have been formed. 
Again, in which sense can it be said that the 
word remolino is incorrectly used by the people 
of Colombia? Are such words as villain, 
charity and many others incorrectly used by 
us because we do not employ them in their 
original significance? Had the compiler of the 
Spanish dictionary in which Mr. Hilder sought 
the definition of the word remolino known of 
its use by the people of Colombia as a name for 
SCIENCE. 
187 
a rounded rock cavity made by an eddying cur- 
rent of water he would probably and very 
properly have given that in his list. Would 
the critic of nomenclature have then thought it 
incorrectly used ? 
OLIVER C. FARRINGTON. 
FIELD CoLUMBIAN MUSEUM, CHICAGO. 
NOTES ON INORGANIC CHEMISTRY. 
An interesting paper on the cause of color in 
minerals by L. Wohler and K. vy. Kraatz- 
Koschlau has appeared in Tschermak’s Mitteil- 
ungen. While many minerals are colored by 
organic substances, the quantity is too small for 
identification. In several cases, as in zircon 
and smoky quartz, the presence of nitrogen 
was proved, and from bases in celestine from 
Gembeck three different double platinum salts 
were obtained. Contrary to the view of Nabl, 
the coloration of amethyst is not due to ferric 
thiocyanate, as no sulfur is present. 
The difficulty of identifying the inorganic 
coloring materials of minerals is no less than 
that of organic; indeed, it was found necessary 
to use synthetic processes exclusively. Chro- 
mium is the cause of color in many minerals. In 
the case of chrome garnets, chrome spinel, 
chrome diopside this is apparent, but is no less 
true in red and violet spinel, ruby, sapphire, 
oriental amethyst, green zircon and topaz from 
Villarica. It was not found possible to detect 
the chromium in ruby and sapphire, but on 
fusing alumina and barium fluorid with one- 
fifth per cent. of potassium bichromate the 
crystals of alumina obtained were chiefly color- 
less, but red, blue, yellow and green crystals 
were also found. From the color differences 
it is probable that the chromium is present in 
different oxydation stages. It was not found 
possible to color alumina by iron, even at very 
high temperature. In the Villarica topaz no 
trace of manganese was present. Wulfenite 
and vanadinite are also probably colored with 
chromium, though organic matter is also pres- 
ent. While titanic acid, and hence pure rutile, 
is colorless, the sesqui-oxid gives a dark brown 
color; hence the color of ordinary rutile is due 
to partial reduction of the titanic acid, a red 
tint being in part due to the presence of iron. 
The color of chrysoprase is due to the presence 
