Vol. XXV. No. 6.] 
POPULAR SCIENCE NEWS. 
83 
from the battery connects, through a vibrating 
bell, with the mercury in the funnel. Upon rais- 
ing the temperature of the bottle to the fusing- 
poiut of the substance, contact is established 
l)etween the two portions of mercury, and the 
Ix^ll is made to ring. The temperature of the 
mercury in the bottle in then noted. 
To Weld Metals to Gla.ss.— M. Cailletet has 
fommunieated to the Societe de Physique a method 
of welding glass and porcelain with metals, which 
may prove extremely useful for instruments of 
research, or for any metallic fitting, such as taps, 
communicating tubes, conducting wires, etc., so 
as to avoid all leakage even under high pressures. 
The process of welding is of the simplest. A 
portion of the tube that is to be welded is covered 
with a very thiu coat of platinum. To obtain this 
deposit, it is sufficient to paint, by the means of a 
small brush, the slightly warmed glass with com- 
pletely neutral chloride of platinum, mixed with 
essential oil of camomile. The essence is made to 
ivaporate slowly, and when the white and colored 
vapors have ceased to be given off, the tempera- 
ture is raised to dull red heat, and the platinum 
l)i'ing reduced covers the glass tube with a bril- 
liaut metallic coating. Connecting the tube thus 
metallically coated to the negative pole of a bat- 
u:vy of suitable energy, it is placed in a bath of 
sulphate of copper. A ring of copper is deposited 
upon tlie platinum, and strongly adheres thereto 
if the operation has been properly carried out. 
SCIEXTIFIC BREVITIES. 
Parasitical Plants.— Chatin has proved that 
:i parasite growing on plants of the Stryehnos ge- 
nus contains neither strychnine nor brucine. The 
mistletoe growing upon the oak does not contain 
the blue tannin of the latter, but exclusively a 
green tannin. In like manner other parasites are 
sliovvn not to absorb the peculiar principles of 
their hosts. 
Uses of Selenium.— Up to the present time 
very little use has been made of the remarkable 
property of selenium in changing its electrical 
(finductivity upon exposure to light. At a recent 
iiHicting of the Physical Society, Mr. Shelf ord 
Uidwell read a very interesting paper on selenium, 
ufid exhibited a selenium cell controlling an elec- 
I lical relay which could be adapted to a variety of 
purposes. In one arrangement it was made to 
work an automatic watch-light, turning on a little 
lamp on the approach of darkness, and extin- 
guishing it again at dawn of day. By another 
arrangement the cell could be used to give notice 
if a railway signal light or a ship's side lantern 
sliould happen to go out. 
Ocean Temperatures were the subject of dis- 
cussion at a late meeting of the Geographical So- 
ciety in London, says the Engineering News. Dr. 
Buchan, who has been for years investigating the 
meteorological aspects of the "Challenger" expedi- 
tion, reported upon this subject. In the expedition 
mentioned, hourly or two hourly observations were 
taken of the atmosphere and surface temperatures ; 
and other observations were made of sea tempera- 
tures at various depths. The result shows that 
the diurnal range of temperature at the surface of 
the open sea is a little less than 1° F. ; while the 
temperature of the air over the sea was about 
three times greater than that of the water sur- 
face, with greater diurnal variations. As to 
thunder-storms, it was found that on land the 
maximum number occurred at mid-afternoon, 
when the air temperature was highest. On the 
open sea 70 per cent, of these storms occurred 
wheu the temperature was lowest. 
©he (Dut-©oop ^orld. 
Edited by HABLAN H. BALLARD, 
President of the Agassiz Association. 
[P. O. Address, Pittsfield, Mass.] 
The importance and the duty of supporting our 
official paper, to which reference was made last 
month, cannot be urged too often or too strongly. 
The Association is bound to furnish three hun- 
dred new subscribers to Popular Science Xews 
during 1891. Of this number only one hundred 
have thus far been credited to us. It seems in- 
credible that the actual number is so small. It 
may be that some persons have sent their sub- 
scriptions this year, owing to their interest in the 
Agassiz Association, without stating that fact in 
their letter to the publishers. If there are any 
such, they will do a simple act of justice, and at 
the same time confer a substantial benefit upon 
our society, by informing the publishers at once, 
so that their subscriptions may be properly cred- 
ited. 
Xearly one thousand members are now taking 
our A. A. course in mineralogy by correspond- 
ence, and are doing very creditable work. The 
course is still open, and any who desire to enter it 
may address Prof. Gustave Guttenberg, Central 
High School, Pittsburg, Penn. 
The President of the A. A. has undertaken to 
prepare a series of books to serve as guides to 
home study in the natural sciences, with a par- 
ticular view to encouraging personal observation 
and laboratory work. Each book will constitute 
a course of twenty-six weeks, with full details of 
such observations and experiments as can be made 
at home with home-made apparatus and with 
practically no expense. The first volume will be 
ready, we hope, by October 1st. It treats of the 
World of Matter^ and includes studies in element- 
ary chemistry and mineralogy. It is intended to 
obviate the necessity for a teacher, and will miss 
its aim if it cannot be read understandingly and 
with interest by anyone possessed of an ordinary 
school education. 
On May 13th was held the quarterly meeting of 
the New York City Assembly of the A. A. Mr. 
G. S. Stanton discussed the "Geology of Manhat- 
tan Island and Vicinity^" and illustrated his lec- 
ture with the stereopticon. Mr. T. Vf. Demarest 
spoke of "Popular Science." Both these gentle- 
men are members of the A. A., and the example 
of depending upon talent inside the society on 
this occasion is worthy of imitation and commen- 
dation. 
»♦* 
The Hyatt Chapter, 490, New York City, has 
issued an attractive programme of its meetings 
for the coming summer and fall. It will be help- 
ful to any who may be considering how to outline 
a similar plan of work, and may be obtained, until 
the edition is exhausted, by addressing, with 
stamp, Mr. G. J. Hake, 3,103 Third avenue. 
A NEW^ Chapter is forming in Christ-Church, 
New Zealand, and another in Hobart, Tasmania. 
There is already a strong Chapter in Port Chal- 
mers, New Zealand. 
^♦^ — — 
The spring programme of the Baird Memorial 
Chapter, 411, Andover, Mass., covers the three 
months ending July 1st, and includes a large vari- 
ety of interesting subjects. Practical analysis 
and dissection are carried on at the meetings. 
Copies of this programme may be had from the 
President of the A. A. 
The first Photogi-aphic Exhibition of the Man- 
hattan Chapter, 89, New York, (B), was held the 
first week in March, and was a brilliant success, 
attracting the attention and winning the commen- 
dation of professional artists. About five hun- 
dred visitors were present. Engrossed diplomas 
were awarded as follows : 
Best Exhibit— Mr. H. T. Rowley. 
Best Landscape— Mr. H. Beeclier, Jr. 
Second Landscape— Mr. H. T. Rowley. 
Best Portrait— Mr. F. Albers. 
Best Group— Mr. W. T. Demarest. 
Chapter 949, New York, (Z), held its Fifth 
Annual Exhibition on April 10. Its fourth course 
of lectures has also been given at its rooms, 49 
VV. 20th street, as follows : 
April 17. " People and Scenery of the Bahamas," 
Dr. J. I. Northrop 
April 24. " Gems and Precious Stones," 
Prof. Sanderson Smith 
<♦> 
WE WILL ANSWER ALL LETTERS. 
The list of Chapters that can be depended on 
to answer all communications is rapidly growing. 
Chapters that do not send in their addresses will 
soon be left "out in the cold." The following 
are added to the lists previously given : 
218, Cornwall, N. Y. — Correspondence with new 
Chapters preferred, but will answer all letters. — 
Miss E. Evelyn Breed, Box 88. 
395, Montreal. — Mineralogy and chemistry. No 
stamps required. — A. II. Ferguson, Box 656. 
.537, Mansfield, O. — Any branch, especially en- 
tomology, botany, and herpetology. — E. Wilkin- 
son, 78 West Bloom Street. 
881, Grand Rapids, Mich. — Mineralogy, botany, 
ornithology, and entomology. All letters an- 
swered. — Edward B. Boies, 23 North Lafayette 
Street. 
Meaford, Ontario. — Kindly say that I will an- 
swer as fully as I can all questions on the miner- 
a'ogyi geology, and botany of this region. Our 
boulders and lake terraces are very Interesting. — 
George C. Albery. 
728, Binghamton, 'N'. Y. — Botany and ornithol- 
ogy are our specialties, but all letters promptly 
answered. — Willard N. Clute, Sec. 
Erie, Penn. — I will answer all letters or cards 
from members of the A. A. I take special inter- 
est in botany.— William Evans, M. D., 2,025 Peach 
Street. 
Waterbury, Conn. — I will correspond on geol- 
ogy, especially Connecticut geology. — 11. N. John- 
son. 
West Bridgewater, Mass.— I will answer all let- 
ters on entomology. Correspondence and ex- 
change particularly desired from the South and 
West. — William D. Tower. 
Niles, Mich.^ — Ornithology, oologj"^, archeology. 
Also, wanted, to exchange, a few rare moths from 
India, Italy, and United States, for books or for 
taxidermist's instruments. — Ralph Ballard. 
Moosup Valley, R. I. — I should be very glad to 
correspond with members of the A. A. interested 
In botany. — S. E. Kennedy. 
Islip, N. Y.— Will reply to any A. A. letters on 
ornithology and oology. The plan is excellent.— 
Johnston Livingstone, Jr. 
