FEBRUARY 26, 1914] 
the use of Government departments only, the public has 
made such large demands for them that an annual edition 
has appeared since the circular was first printed in 
tgo7. Another circular for which the demand is likely 
to be extensive is that on copper wires, prepared at 
the request of the American Institute of Electrical 
Engineers. It contains nearly seventy pages of tables 
and other information about copper wire, brought 
thoroughly up to date, last year’s work of Mr. G. L. 
Heath on the relation between the purity and tem- 
perature coefficient of resistance of wires being 
included. 
Tue January number, which begins the career of 
the Annales de Physique as a separate publication, 
consists of ninety-six pages of the same size and style 
as the Annales de Physique et de Chimie have made 
us familiar with in the past. The annual yolume is 
to extend to nearly 600 pages, and the price outside 
France is to be 28 francs. Profs. Lippmann and 
Bouty are the editors, and the first number is certainly 
a credit to them. It contains a communication by 
M. Violle on physical units to be adopted in France, 
a second by M. Brillouin on a relation between specific 
heat and radiation of a body independent of the 
quantum hypothesis, a third by M. Marcelin on the 
thickness of films spread on the surface of water, in 
which it is shown that the thickness of a camphor 
film may be as small as the diameter of a camphor 
molecule, and, lastly, the first part of a long paper 
by M. Croze describing experiments on the emission 
spectra of the commoner gases 
A CIRCULAR (No. 43) has been issued by the Bureau 
of Standards at Washington with reference to the 
international metric carat of 200 mg., which was 
adopted on July 1 last by the United States customs 
Service as the unit for determining the import duties 
on precious stones. Tables of equivalents are included 
in the circular, which will be useful to diamond dealers 
in converting from the old unit to the new and vice 
versa. The value adopted for the old carat is 
205-3 mg., which is the average weight of the various 
carats previously in use in the United States. This is 
precisely the same value as that of the old carat 
hitherto used in the United Kingdom, which is to be 
displaced on April 1 next by the metric carat of 
200 mg., in accordance with the Order in Council of 
October 14 last. The tables would accordingly be 
useful also to British jewellers for conversion pur- 
poses; they are much more complete and practicable 
than those issued by some American firms of gem 
dealers in the form of “folders,” and are followed by 
some valuable hints on the care and use of balances 
and weights for weighing precious stones. 
Tue July to December, 1912, number of Isis, the 
publication of the Dresden Society for Natural Know- 
ledge, contains a paper by Mr. H. Dember on the 
relationship between atmospheric electricity and wire- 
less telegraphy. The theory has been advanced that 
electric waves suffer reflection from an jonised layer 
in the upper atmosphere, and that the development 
of this layer by day causes the difference between day 
and night wireless phenomena discovered by Marconi. 
The author’s object was to secure direct evidence of 
NO. 2313, VOL. 92] 
NATURE 
723 
such ionisation. As ultra-violet light is rapidly 
absorbed by the earth’s atmosphere, he pursued his 
inquiries in Switzerland, near Arolla, at considerable 
heights, the one 2000, the other 3400 metres, above 
sea-level. The ionising action of sunlight, it is 
argued, must increase equally the number of negative 
and of positive ions. The latter normally preponderate 
in number, thus sunlight must tend to increase the 
ratio borne by the number of negative to the number 
of positive ions. The free ionic charges in the atmo- 
sphere were observed in the usual way with Ebert’s 
apparatus, while the ultra-violet radiation was simul- 
taneously measured by a simple apparatus designed 
by the author. The results of the observations, which 
were made on five days in August and September, 
1911, are illustrated by figures, which show on the 
whole a parallelism between the variations of the 
ultra-violet radiation and the magnitude of the ratio 
of the ionic negative to the ionic positive charges. 
The author allows that the observed effect, even at 
3400 metres, was probably due in large part to a 
vertical current or convection of ions produced at 
greater heights in the atmosphere. The same paper 
describes some interesting observations on the absorp- 
tion of sunlight of various wave-lengths made in 
August, 1912, in the Italian Alps, with a new appa- 
ratus. The results are discussed in reference to Lord 
Rayleigh’s theory of atmospheric action. 
THE “Wratten and Wainwright Division” of 
Kodak, Limited, have just issued a fifty-page pamphlet 
on reproduction work with dry plates. They make out 
a very strong case for the use of panchromatic gelatine 
plates in direct screen negative making for three- 
colour work, claiming not only that gelatine is as 
good as collodion, but that it is much preferable, when 
the photographer has become accustomed to it. But 
the plate must have a fine grain, be very sensitive to 
red and green, and give great density and contrast, 
characteristics which are found in the Wratten process 
panchromatic plate, which is rendered colour sensitive 
by “bathing,” that is, immersion in the dye solution 
after the plate is coated. The pamphlet is intended 
for the guidance of the block-maker, and gives detailed 
suggestions with regard to each step in the process. 
We learn that the laws of geometrical projection are 
good and sufficient guides for regulating screen- 
distance, so that after the innumerable pages that have 
been written on this subject, the whole matter may, 
for practical purposes, be expressed in a line or two. 
The reason why greens are so difficult to reproduce is 
fully explained. A choice of six pairs of colour filters 
for two-colour work is given, and there are several 
other items of interest, even to those who regard such 
matters from a merely theoretical point of view. 
Mucu interest was aroused by the preparaticn in 
1g10 of an optically-active oxime of the formula 
Bx af Hig 
| HO.CO” \cH,—CH,” 
The preparation of this compound afforded the first 
concrete evidence that the three bonds of the nitrogen 
atom were not in a plane, and so provided a solid 
| foundation for the theory which Hantzsch and Werner 
had put forward in 1890 to account for the isomerism 
=N.OH 
