SCIENCE—ADVERTISEMENTS 
New Apparatus 
for producing 
Ulira-Violet Radiation 
@ 
4 
The portable outfit illustrated herewith 
produces an abundance of ultra-violet radia- 
tion with which a number of very interesting 
fluorescent effects may be produced. 
_ For example, the following curious prop- 
erties may be readily demonstrated :— 
If the light from the iron spark is directed 
on a lump of willemite, the latter will glow 
with a beautiful green fluorescence. If a thin 
plate of glass or clear mica is now placed be- 
tween the iron spark and the willemite, the 
green fluorescence of the latter will instantly 
vanish, and it will appear inits natural color 
as seen by daylight or any ordinary artificial 
light. Ifnow a plate of clear quartz or sele- 
nite is substituted for the glass or mica, the 
willemite will continue to glow with its char- 
acteristic green fluorescence. It is thus made 
evident that the glass and mica are opaque to 
the ultra-violet rays which produce fluores- 
cence, while the quartz and selenite are trans- 
parent to them. This experiment may be 
tried with any fluorescent substance other 
than willemite with similar results. 
The outfit operates on 110 volts (60 
cycles) alternating current—and requires 
about 300 watts. 
If interested, please write for Descriptive 
Bulletin X 223 
JAMES G. BIDDLE 
1211-13 ARCH STREET 
PHILADELPHIA 
Memoirs of the Wistar Institute of Anatomy and 
Biology. No. 6, 1915 
THE RAT 
Data and Reteeence Tables. 278 Pages. 89 Tables. 
Bibliogr é 
Ciapiled: sud Edited by HENRY H. DONALDSON. 
Postpaid, $3.00. 
The Wistar Institute Philadelphia, Pa. 
The Microscope 
12th Edition, Published April 10, 1917 
Re-Written and largely Re-Illustrated 
By SIMON HENRY GAGE of Cornell University 
Postpaid $3.00 
COMSTOCK PUBLISHING CO., Ithaca, N. Y. 
MARINE BIOLOGICAL LABORATORY 
WOODS HOLE, MASS. 
Biclogical Material 
1. Zoology. Preserved material of all types of animals 
for class work and for the museum. 3 aS 
2. Embryology. Stages of some invertebrates, fishes (in- 
cluding Acanthias, Amia and Lepidosteus), Amphibia, and 
some mammals, 
3. Botany. Preserved material of Algae, Fungi, Liver- 
worts and Mosses. Price lists furnished on application to 
GEORGE M. GRAY, Curator, Woods Hole, Mass- 
Teachers Wanted 
We have a steady demand for men in all depart- 
ments of Science for Agricultural Colleges, and Uni- 
versities. Special terms. Address 
The Interstate Teachers’ Agency 
Macheca BHig. New Orleans, La. 
“Detroit” Laboratory Burner 
The Standard Burner for Laboratory uses of every char- 
acter—most economical to operate. 
It produces a stiff, blue flame of maximum temperature, 
without use of Air Blast. i 
Separate control of both air andgas. Will not flash back, 
clog or sing. 
Guaranteed to work on any kind of gas—city coal gas, 
natural or gasoline-gas. é 
In your next order specify the ‘“‘ DETROIT” and get the 
best. The name “DETROIT” is stamped on the burner— 
look out for imitations. Ask us for name of dealer in your 
vicinity, or order direct. 
Prices: Less than doz. lots, $1.25 each; Lots of 1 doz. 10 per 
cent. discount; Lots of 12 doz. 20 per cent. discount. 
DETROIT HEATING & LIGHTING 
COMPANY 
612 Wight Street Established 1868 DETROIT, MICH. 
