SCIENCE. 
197 
THE CUPRIFEROUS SERIES IN MINNESOTA * 
Thepaperof Prof. N. H. Winchell, State Geologist, of Min- 
nesota, was a brief statement of the relations of that formation 
to the ranges of crystalline rock that form the northwestern 
border of the Lake Superior Basin. He concluded, by two 
lines of investigation, that the Cupriferous series is of the 
age of the New York Potsdam, and that it falls within the 
horizon of some part of that group which the Canadian ge- 
ologists have designated the Quebec. 
One line of argument related to an examination in the field 
of the stratigraphy, in which the sedimentary beds are seen 
to pass by metamorphic changes through various forms to 
fully crystalline rocks styled granite and gneiss. These 
crystalline rocks, which are spread over large areas, are in- 
timately associated with the igneous rocks of the Cuprif- 
erous Series, from which, however, they are constantly dis- 
tinguished by certain mineralogical differences The writer 
also parallelized the igneous beds of the northwestern coast 
ranges with the Labradorite, or Norite, rocks of Canada, 
and suggested the possibility that the “ Laureutian ” Eozoon, 
said to occur in this terrane, may be of the age of the Low- 
er Silurian. 
ON COLOR BLINDNESS* 
By Dr. B. Joy Jeffries. 
Dr. Jeffries first described the natural condition of the 
color-sense, and illustrated some of its peculiarities relating 
to color-blindness. The complimentary after-image of a 
color can be readily seen by gazing at the red setting sun, 
when, if we turn our eyes to the east, we shall see a green 
rising one. Looking steadily at a yellow spot on white, 
and turning awaj 1 , we see a blue one, etc. After looking 
intently at the red or green light on a railroad or vessel, one 
cannot help momentarily seeing the reverse color. The 
centre of the retina has the greatest power of form-percep- 
tion; we must fix our eye steadily to see anything very dis- 
tinctly. The same with color. All colors fade in intensity 
outward from the centre of the retina. In a central zone 
we can distinguish all three of the colors now considered 
primary, viz., red, green, and violet. In a zone outside of 
this our red perception fails, and^n the outer portions still 
of the retina green fails, and we*see blue or violet only. 
Now, we ha ve red, green, and violet blindness, resembling, 
so to speak, the conditions of these zones. This must not, 
however, be too strictly construed. Color-blindness may 
be best described thus: Those who are red or green Cone 
involving the other) or violet-blind see all objects having 
these colors as gray or grayish in the proportion in which 
they are color-blind and the depth of the pigment. A color 
mixed with their faulty one will be, so to speak, muddy. 
Many thousands of examinations have been made all over 
the world, with the same result. He has tested 17,695 males, 
finding 739 color-blind in greater or lesser degree, viz., 
about 4 per cent. In females it is very rare, which, how- 
ever, their familiarity with the colors does not account for. 
He tested 13,893 females, finding only ten color-blind. 
Age, race, color, education, condition of civilization — all 
seem to have no effect, as tests have been now made from 
the north pole to the equator, and throughout Europe and 
America. It is congenital, and largely hereditary, It may 
be artificially produced by putting a person in a cataleptic 
or hypnotic state; also those color-blind who can be put 
in this state can be temporarily relieved of their defect. 
It may be cured by tobacco and alcohol poisoning, by in- 
juries affecting the head, and by disease. It is a symptom 
of some brain disease of constitutional origin. 
It can be palliated by gas light, or by looking through 
pale lemon-colored glass, or by looking through a solution 
of the aniline dye called fuchsine. All this does not cure, 
but simply changes the relations of light and shade for the 
color-blind, by which alone they distinguish their faulty 
colors. The reader briefly described how difficult it was 
formerly to detect color-blindnes, and referred to his man- 
ual in explanation of the manner in which persons affected 
escape. Thanks to recent observers and workers in the 
field we now have methods which are simple, and readily 
and quickly carried out by competent experts. 
* Read before the A. A. A. S., Boston, 1880. 
These facts have led the United States Government to 
undertake its control in the arm}', navy, and marine hospi- 
tal service. Unusual examination of seamen is not yet 
compulsory. Its great value to the sailor was particularly 
explained. Standard tests and standard powers of sight 
and color-perceptions are not yet determined by the United 
States. An International Commission to determine these 
has been proposed in a bill now before Congress. The 
future value of such a commission was explained, and the 
audience urged to assist in having the system carried out. 
As to the railroads of the country, Dr. Jeffries quoted 
from his book, now a United States manual ; “The diffi- 
culties are very great. Here the interests and the safety of 
the community have to contend with ignorance, prejudice, 
pecuniary considerations and incredulity born of supposed 
immunity from danger.” This has proved most true, and 
even at this date, three years and a half since he, in this 
same room, called public attention to the danger from color- 
blindness, but one State, Connecticut, has passed laws con- 
trolling color-blindness and visual defects among railroad 
employes. And here in this State most violent attempts 
have been made to prevent the action of the law in protect- 
ing the community, even politics being introduced. 
The practical tests, approved of over the world and rec- 
ommended at the International Medical Congress at Amster- 
dam, September, 1879, and directed by the Connecticut 
Board of Health in charge of the control, were then thor- 
oughly shown and explained. Practical illustration was 
also given the audience by a color-blind gentleman who 
kindly consented to exhibit his infirmity in the cause of sci- 
ence. These tests were Holmgren’s with the colored wors- 
teds (used by Dr. Jeffries in our public schools and the as- 
sociation), Donders and Daae’s modification of this method. 
Stilling’s pseudo-chromatic cards, Woinow’s disk, Pfliiger’s 
letters, and finally Donders’ method with reflected light and 
transmitted light, and Holmgren’s with colored shadows, — 
these last two being for the purpose of determining the 
quantitative color-sense so necessary in deciding the fate of 
a railroad employd or pilot. The simple, practical use of 
these methods in the hands of competent experts was 
shown and proved in testing thereby the color-blind present. 
Dr. Jeffries explained in detail how theoretical was the at- 
tempt to decide the color-sense by lanterns and flags used 
on land or sea, and how readily mistakes would thus be 
made. The worsted test can, by competent experts, be 
quickly made in the paymaster’s car, for instance, whereby 
no man is taken from his duty. The color-blind can thus 
be sorted out, and subsequently re-examined with these ad- 
ditional tests as a means of control, and to exhibit their 
precise defect to those in authority. During and after the 
reading of the paper color-blind gentlemen present were ex- 
hibited, to their astonishment and to that of the bystanders. 
All present were asked if convinced by what was shown of 
the danger, to exert their influence in the cause of control of 
color-blindness. Dr. Jeffries stated in conclusion that he had 
hoped to have been able to touch upon the most interesting 
point of the development of the color-sense and the educa- 
tion of our color-perception. He was, however, only able 
to briefly refer to the work going on of the study of color 
development, and particularly the contributions to it by his 
friend Dr. Hugo Magnus, of Breslau. Dr. Jeffries’ work 
in testing all the Boston school-children showed, as it 
has elsewhere, the great ignorance on the part of males of 
color-names, aside from color-blindness. He exhibited 
Dr. Magnus’ color-chart for teaching children colors and 
their names, which received a diploma of honor from the 
International Medical Society at Amsterdam. The use of 
this he explained, and said he was engaged with Mr. Prang 
in its introduction into this country among our schools, both 
private and public. The great purpose of this special work 
being to teach the child to associate with the word the color 
and the color sense, as well as the mere color names. 
Occurrence of Ozone on Evaporation of Different 
Liquids. — A few drops of ether or alcohol are let fall upon 
a paper equally moistened with cadmium iodide-starch so- 
lution, and the volatile liquids set on fire. After their co- 
operation the paper is found to be turned blue from the 
formation of ozone. — Polyt, Notizblatt. 
