May 14, 1914] 
NATURE 
269 
the atomic weight, 1-31. Very simple elements can 
exist therefore in which the atomic number differs 
from the number of electrons, and Dr. van den Broek’s 
hypothesis cannot be a complete principle, although 
perhaps satisfactory for the stable terrestrial elements. 
Nevertheless, if it is satisfactory in this range, Bohr’s 
theory is not. J. W. NicHOLsoN. 
King’s College (University of London). 
Temperature-Difference between the Up and Down 
Traces of Sounding-Balloon Diagrams. 
In his paper on the daily temperature change at 
great heights (January issue of the Quart. Journal of 
the Roy. Met. Soc.), Mr. Dines deals with the double 
traces shown by the diagrams of registering-balloons. 
He ascribes the difference for a great deal to the 
heating effect of the balloons, as the instruments swim 
in the wake of dead but heated air that follows the 
ascending balloon. 
He rejects as a possible cause any thermal lagging 
of the instrument, because the double trace is most 
apparent in the isothermal layer, and also because it 
meastly occurs by day and not by night. 
Receiving this number of the Quart. Journal, it just 
happened that I had made a synopsis of this kind of 
temperature-difference for the Batavian ascents, 
which throws another light on this question. 
At Batavia the balloons are of a larger type than 
those used in England; also the string between balloon 
and instrument is much longer, measuring 30 m. and 
more. Moreover, it has been observed in numerous 
cases that up to the greatest heights the whole system 
of balloon-parachute-instrument often swings strongly. 
Accordingly any heating effect by the air in the wake 
of the balloon seems most improbable. 
The instruments are of the pattern usual on the con- 
tinent and made by Bosch (Strassburg); they are 
provided with clockwork. When possible the heights 
have been calculated separately for the ascent and 
the descent; thus, when the downward temperatures 
were found to be lower than the upward, the corre- 
sponding heights became lower, and accordingly the 
difference of temperature for the same calculated 
height in the ascent and the descent was increased. 
In half of the thirty ascents which up to the present 
have been made, the balloon was liberated 1-13 hours 
before, and in the other half 1-134 hours after sunrise. 
Thus, in the first cases only the latter part of the 
descent took place at an hour that solar radiation 
begins to be active. 
The mean differences found are :— 
Temperature Higher in the Ascent than in the 
Descent. 
Before After 
Heicht sunrise sunrise Number of cases 
in km. aC. Le Before After 
To pace GG o4 16 14 
2 Oi O-4 18 14 
3 0-4 0-9 18 16 
4 0:2 1-4 18 16 
5 Gz 5 i 15 
6 74 2-4 16 15 
7 1-0 3:0 7 12 
8 1-2 3°3 I5 13 
9 1-3 3-2 15 12 
10 2:2 4:4 15 II 
II 2:7 4:6 15 Il 
12 3:0 4:3 15 II 
13 3°4 5:0. 15 10 
14 38 3°6 13 9 
i) 3°3 ae, 12 9 
16 3°5 25 6 5 
NO. 2324, VOL. 93| 
| 
| 
| 9:2°. 
| only, 
affected by a systematic error. 
The prominent fact, demonstrated by this table, is 
that up to 13 km. the differences before sunrise are 
much smaller than those after sunrise. 
The synopsis teaches, that before sunrise negative 
values occur in all heights, especially below 7 km. 
In one case up to the stratosphere the difference was 
negative in all heights. 
On the contrary, in another ascent it went up to 
After sunrise no ascent, with negative values 
occurred, and in one case the _ differences 
amounted to 11-2°. 
For the stratosphere, only in eight cases a set of 
these differences was obtained, its height being so 
great in these low latitudes that only part of the 
balloons reach its layers. Only in one of these cases 
(after sunrise) the descent-temperatures in the strato- 
sphere exceeded those of the ascent, and in another 
case (before sunrise) higher temperatures alternated 
with lower. 
In the five other cases (before sunrise) the sign of 
the differences in and below the stratosphere were 
contrary. It must be borne in mind that scarcely any 
isothermal state prevails in the tropical stratosphere, 
but that the temperature increases with the height (cf. 
my letter in Nature of March 5, p. 5). 
However, in the above-mentioned case of alternating 
positive and negative values, isothermal condition was 
met with up to 23 km. 
The reversal in sign of the difference, which accom- 
panies the reversal of the temperature gradient, strongly 
points to a thermal lagging of the instrument. Its 
heavy parts, and the basket also, will lag strongly 
and will influence the thermograph. In the ascent 
the lesser the ventilation the greater the heating. 
Thus the influence will increase with the height, as 
the ventilation decreases. In the descent the ventila- 
| tion in most cases was greater than in the ascent, and 
accordingly the negative lagging less. After sunrise 
the thermal lagging of the basket will be enhanced 
in the ascent by sun-radiation, which easily explains 
the fact that the differences are larger after than 
before sunrise. 
Perhaps the English instruments, being smaller 
than the German, have a smaller thermal lag 
than the latter. Thus Mr. Dines’s explanation may 
be applicable to the facts observed in England, and 
mine to those met with in Java. From them I think 
the following lessons may be learnt, which applies to 
most Continental ascents made in a similar way and 
with the same pattern of instruments :— 
(1) The temperatures of ascent and descent should 
be averaged. 
(2) When descent or ascent is available only, a 
| mean correction, to be derived from a large number 
_ of corresponding cases, should be applied. 
(3) The temperatures and heights taken from the 
publication of the International Committee, in which, 
in most of the cases, ascents only are given, are 
W. van BEMMELEN. 
Batavia, March, 1914. 
Gellular Structure of Emulsions. 
THE same arrangement that is shown by Fig. 2, in 
Nature of May 7 (p. 240), may be seen in an emulsion 
of Oriental finely powdered coffee suspended in milk 
and water. I have supposed that it is connected with 
a strange phenomenon which I reported in NATURE 
about forty years ago. Sooty rain-water, after stand- 
ing for some hours, will develop clear planes of 
water, as much as 10 cm. long and only 1 or 2 mm. 
wide. These planes are most readily seen by candle 
light when vertical, but may develop at any inclina- 
