154 
he holds proves that the so-called ‘retinal light’ 
is really ‘cerebral light.’ The experiment which 
he considers conclusive consisted in looking at 
a dimly lighted window in a dark room, the 
window being so dimly lighted that both the 
retinal figures and the window could be seen. 
He then moves the eyeballs with the fingers 
and notices that the retinal figures are station- 
ary, while the image of the window moves. 
Dr. Scripture apparently confuses movement 
of the retina and movement on the retina. 
What he calls movement in the case of the 
image of the window is evidently movement of 
the image on the retina as shown by the ‘local 
signs’ of the retina. But the retinal figures, 
being impressed on the retina, move with it and 
not on it, and therefore the local signs of the 
retina give no evidence of its movement. 
In repeating the experiment I gazed fixedly 
at the window for some time. In closing my 
eyes I had impressed on the retina, in addition 
to the retinal figures, a faint after-image of the 
window. If the eyes were now moved, as 
Dr. Scripture directs, no movement was no- 
ticeable in the after-image. It did not separate 
into two moving images, for this would neces- 
sitate a change in position of the two images in 
relation to corresponding points of the two 
retinas. If two dissimilar after-images are im- 
pressed, one on each retina, and the eyeballs 
pressed, they, for the same reason, will show 
no relative motion. Why, then, should we 
not expect the retinal figures to remain single 
and immovable, as Dr. Scripture found them 
to be? 
KE. B. WHEELER. 
MISSOURI STATE UNIVERSITY, July 24, 1899. 
NOTES ON INORGANIC CHEMISTRY. 
Two reports have recently been presented to 
the Home Office in Great Britain which are of 
considerable general interest, one on the use of 
yellow phosphorus in matches, and the other 
on the use of lead in pottery glazes. The first 
of these reports is by a commission consisting 
of Professors T. E. Thorpe, 8S. Oliver and Dr. 
Cunningham, and the other by Professors 
Thorpe and Oliver, and both have been re- 
viewed at some length in Nature. Only two 
kinds of matches seem to be considered, the 
e 
SCIENCE. 
[N. 8S. Vou. X. No. 240. 
‘strike anywhere,’ which is tipped with yellow 
phosphorus, and the ‘safety,’ in which red 
phosphorus is used, and is not on the match, 
but on the striking surface of the container. 
According to the report no danger seems to at- 
tend the manufacture where red phosphorus is 
used. In the case of yellow phosphorus, the 
dangerous processes are mixing the paste, dip- 
ping the matches, drying and boxing, this last 
involving the most handling. Already existing 
rules in Great Britain require efficient ventila- 
tion, non-employment of laborers who have suf- 
fered with necrosis or have lost a tooth, imme- 
diate medical examination of. persons suffering 
with toothache, notification of cases of necrosis, 
and proper washing conveniences. The imme- 
diate question before the commission was as 
to whether they should recommend the prohi- 
bition of yellow phosphorus. In view of the 
competition of other countries, notably Belgium, 
Sweden and Japan, for export trade, and, asit 
has been shown that proper precautions can 
prevent danger in manufacture, it was felt wise 
not to prohibit the use of yellow phosphorus, 
unless an international agreement could be 
reached. They suggest, however, more precau- 
tions, and point to the Diamond Company, of 
Liverpool, where no cases of phosphorus ne- 
crosis have ever occurred. Unless we are mis- 
taken, not a few of the American manufacturers 
have solved successfully the problem of tipping 
the match itself with a paste of amorphous 
phosphorus, while the use of the ‘safety 
matches’ is, happily, rapidly increasing. 
The report on lead glazes is more far-reach- 
ing in its recommendations, but, according to 
W. Burton, in Nature, is hardly practical. The 
recommendations are as follows: (1) Prohibi- 
tion of lead glazes in seven-tenths of the 
wares produced in the potteries ; (2) That in the 
other three-tenths lead should be used only in 
the form of a lead silicate frit ; (8) The use of 
lead white in glazes or colors absolutely prohib- 
ited ; (4) Prohibition of women and children in 
all processes where they would come in contact 
with the lead work. Mr. Burton would agree 
to the second and third recommendations, but 
considers the first and last impracticable, on ac- 
count of the difficulty of replacing lead glazes 
by leadless glazes for many wares, and on ac- 
