Marcw 15, 1901. ] 
but this is questioned by Saltet, who finds that 
different micro-organisms are concerned in the 
process, and that the reduction proceeds in 
stages, as is the case with the reduction of 
nitrates to ammonia. Saltet has isolated a 
new micro-organism, Bacillus desulfuricans, 
which reduces sulfates to sulfites, but produces 
no hydrogen sulfid. 
Ir has been found by Matignon that metallic 
magnesium liberates from their oxids not only 
thorium, cerium and lanthanum, but also 
praseodymium, neodymium and samarium. 
Nitrogen, but not argon, is rapidly absorbed 
by all of these metals. When the last three 
are obtained from their oxids in the presence 
of hydrogen, they unite with it to form hydrids, 
which are dissociated when strongly heated. 
Moissan finds that the carbid of samarium, 
SmC2, can be formed in the electric furnace in 
minute, transparent, yellow, hexagonal crys- 
tals. It is decomposed by water, the chief 
gaseous product being acetylene, though con- 
siderable hydrogen and members of the paraffin 
series are also formed. In this action it 
closely resembles the carbid of yttrium. 
THE fact that Dewar has found hydrogen to 
be a constituent of the atmosphere gives much 
interest to the discovery of Gautier, that hydro- 
gen is formed by the action of water on granitic 
rocks at temperatures considerably below a red 
heat. In one experiment a granite rock was 
heated with phosphoric acid and gave 1,400 cc. 
of gas per kilo, 916 cc. of which was hydrogen. 
With water, the quantity liberated is somewhat 
less. Ammonia is formed at the same time, 
and Gautier concludes that both these gases are 
derived from the action of water on nitrids, 
chiefly iron nitrid, though possibly some of the 
hydrogen may come from carbides. Matteucci 
found during a recent eruption of Vesuvius, 
pieces of rock, coated with ammonium chlorid 
and iron nitrid, which would seem to show a 
close relation between these substances. 
In a short paper in the Berichte, Giesel con- 
firms the observation of Walkhoff as to the 
effect of radio-active substances on the skin, 
similar to that of the Rontgen rays. He 
placed a celloloid capsule containing a quarter 
of a gram of radium, under his arm, and in two 
SCIENCE. 
435 
hours a slight reddening was apparent. In the 
course of two or three weeks considerable inflam- 
mation was present, with darkening, and finally 
loss of the skin. A similar action was found to 
take place on the leaves of living plants, and 
salts, glass and paper were also affected. 
J. L. H. 
ZOOLOGICAL NOTES. 
Dr. ANTONIO Porra, of the Institute of 
Zoology and Comparative Anatomy at the 
University of Parma, has lately published in 
the Proceedings of the Royal Institute of 
Science and letters of Lombardy his researches 
on Aphrophora spumaria and, in a footnote, 
he says, ‘‘I had already finished the present 
paper when I received a pamphlet by Pro- 
fessor Morse in which he discusses the forma- 
tion of the froth in the Aphrophora spumaria. 
It was with genuine satisfaction that I found 
there a confirmation of observations that I had 
made. Moreover, I repeated one of his ex- 
cellent experiments, which leaves no doubt 
whatever of the fact that the insect emits a 
liquid only. Placing a larva on a piece of ab- 
sorbent paper in order to dry it and then upon 
a glass, if we allow a drop of our saliva to fall 
upon it, it begins to fill this liquid with air- 
bubbles.’’ 
It is a curious fact that Mr. Morse gave an 
account of the manner in which the so-called 
spit-insect makes the froth on grass in his ‘ First 
Book of Zoology’ twenty-five years ago. Ger- 
man editions appeared in Stuttgart and Berlin, 
an English edition was also published, and 
finally the book was translated into Japanese, 
and yet every general work on entomology 
has repeated the erroneous ideas regarding the 
habits of this creature. Even the last volume 
of the Cambridge Natural History series con- 
tinues the error. In May of last year Mr. 
Morse published in the Popular Science Monthly 
an extended account with illustrations explain- 
ing more in detail the habits of the larva, and 
its method of forming the froth and it is to this 
paper that the Italian naturalist refers. 
NOVA PERSEI. 
PROFESSOR EDWIN B. FROST writes to the 
Astronomical Journal from Dartmouth College, 
