He 
pe 
SCIENCE.—AD VERTISEMENTS. 
Scientific Apparatus 
“ Bowboin”? X-RAY Focus TUBE. 
My Specialties Are: 
“«W-S”’ X-Ray Apparatus; Weston Ammeters, Volt- 
meters and Wattmeters; ‘‘Chlorid Accumulator’’ Stor- 
age Batteries; Electrical Measuring Instruments; Phys- 
ical and Optical Apparatus; Pyschological Apparatus, 
ete. 
‘¢ Duty Free’’ Importations from all prominent 
European makers. 
Correspondence requested. 
JAMES G. BIDDLE, 
Dealer, Manufacturer’s Agent and Importer, 
909 Drexel Building, PHILADELPHIA. 
Dec. 1, 1896. Just Published. Sixth Edition of 
THE MICROSCOPE 4X2, Microscopt- 
CAL METHODS, 
By SIMON HENRY GAGE, Professor of Microscopy, His- 
tology and Embryology in Cornell University and the 
New York State Veterinary College, Ithaca, N. Y., U.S A. 
Sixth edition, rewritten, greatly enlarged, and illustrated 
by 165 figures in the text. Price, $1.50, postpaid. 
COMSTOCK PUBLISHING CO., Ithaca, N. Y. 
Cambrian Fossils A large collection of Upper 
Mississippi Cambrian fossils 
from the St. Croix (Potsdam) sandstone for sale. Mostly 
Trilobites. Send for low prices. 
W. A. FINKELNBURG, WINONA, MINN. 
NEW CATALOGUE. 
We have recently issued a new edition, revised and en- 
larged to 64 pages, of our catalogue of 
Books on Chemistry, Chemical 
Technology and Physics. 
It is arranged by subjects, and includes all the standard 
books in Chemical and Physical Science, as well as the re- 
cent literature up to date. 
A copy of this Catalogue will be sent free by mail to any 
address. 
D. Van Nostrand Company, 
Publishers and Importers of Scientific Books, 
23 Murray St. and 27 Warren St., New York. 
@-:-@ 
Delicious 
Drink 
Horsford’s Acid Phosphate 
with water and sugar only, makes a 
delicious, healthful and invigorating 
drink. 
Allays the thirst, aids digestion, and 
relieves the lassitude so common in 
midsummer. 
Dr. M. H. Henry, New Vork, says: ‘‘When 
completely tired out by prolonged wakefulness 
and overwork, it is of the greatest value to me. 
As a beverage it possesses charms beyond any- 
thing I know of in the form of medicine.” 
Descriptive pamphlet free. 
Rumford Chemical Works, Providence, R. I. 
Beware of Substitutes and Imitations. 
RARE MINERALS. 
THAUMASITE, from Paterson, N. J., asulphate, silicate and 
carbonate of calcium, pure white, 25c. 
EKDEMITE, bright yellow on red wulfenite, Arizona, 50c. 
NATIVE ARSENIC, Japan, 4 to 34-inch crsytallized balls 
25c, 35c. = 
Collections for Schools. 
ALPHA COLLECTION, twenty-five specimens in trays, con- 
tained in a neat wooden box and accompanied by a /6- 
page guide book (XIII., Guide for Science Teaching, Bos 
ton Society of Natural History), Price, complete, $1.00. 
CABINET COLLECTIONS, 100 specimens, small size, $5.00. 
100 specimens, large size, $10.00. These specimens are 
each accompanied by a label giving name, system of 
crystallization, chemical formula, and locality, and make 
a good working collection for a student. 
EXCELSIOR COLLECTION for high schools and colleges 
200 specimens, nicely mounted on wooden blocks, with 
beveled fronts for receiving labels. Price, packed 
$100.00. School Bulletin just out. 
Loose Crystals. 
Small packages of free crystals for crystallographic study 
may be sent for inspection by mail at small cost. Ap- 
proyal boxes of cabinet specimens by express or freight. 
ROY HOPPING, 
MINERAL DEALER, 
504-506 Liberty Building, 
Liberty and Greenwich Sts. NEW YORK. 
