a * mrt oy eX, 
~ Marcu 17, 1923] 
made to elucidate the structures accurately to enable 
the extent of the resources available to be calculated. 
Actual oil and gas possibilities are practically negli- 
ible, but the shales at places like Albert Mines and 
osevale are both well known and valuable, while 
several other localities offer good prospects. Since 
May 1921, the D’Arcy Exploration Co. (a subsidiary 
of the Anglo-Persian Oil Co.) has been operating at 
Rosevale, mainly on experimental lines with a special 
type of retort (Wallace), and the results have so far 
proved quite satisfactory. The average recovery of 
oil from a ton of shale is about 30 gallons, the specific 
ged of the product varying from 0-893 to 0-903. 
is compares favourably with that obtained from the 
Scotch retort on the same material, where the yield is 
less and the gravity of the oil usually higher. Some 
gypsum and anhydrite deposits described from the 
Tegion also form interesting and economically valuable 
occurrences; these are in the Hillsborough Series of 
Mississippian age and are at present being worked in 
the Demoiselle and Hillsborough basins. The rela- 
tionship of the gypsum to the anhydrite deposits 
appears to be obscure here, as is frequently the case» 
elsewhere ; but the theoretical problems to be solved 
have a direct bearing on the future working of the 
deposits. 



































. 
CLoup Formation.—The Royal Magnetical and 
Meteorological Observatory of Batavia, in Verhande- 
lingen, No. 10, gives a discussion by Dr. C. Braak on 
cloud-formation, nuclei of condensation, haziness, 
and dimensions of cloud-particles. The data were 
determined by means of Aitken’s dust counter. In 
addition to the observations made in the East-Indian 
Archipelago an appendix is given on observations 
made in the Indian Ocean during a voyage from 
ava to Europe. Observations were also made on 
fog in the Archipelago as well as in other regions. 
Individual observations are published, so that the 
details can be examined. The differences between 
land and sea are given, and the variations with height 
above sea-level. The number of nuclei in the open 
‘sea under humid conditions was 120 per c.cm., and 
in the open sea in the dry season 1620 per c.cm.; in 
the neighbourhood of the land the mean number 
was 2560. The variation with height above sea- 
level shows a great decrease in the number of nuclei 
with increased height. Seasonal variations are con- 
sidered, dealing chiefly with observations in Java and 
Sumatra. Much of the haze experienced is attributed 
to smoke from forest and prairie fires. The size of 
the particles is said to have a larger influence than 
their number on the density of haze, careful observa- 
tions being made with a microscope to test this view. 
Valuable generalisations haye been made on the 
subject, and these will doubtless be tested by other 
observers. This paper was taken as the subject for 
discussion at the evening meeting at the Meteoro- 
logical Office on February 5, and is referred to in 
the Meteorological Magazine for February. 
Tue ELecrricat Conpuctivity oF GLass.—The 
February issue of the Journal of the Franklin Institute 
contains a communication from the director of the 
Applied Science Section of the Nela Research 
Laboratories, giving the results of the research of 
Mr. L. L. Holladay on the conductivities of glasses 
at temperatures up to 500°C. Between 20° and 75°C. 
the resistance from the inside to the outside of the 
glass tubes used was measured, and at higher tempera- 
tures the resistance of a length of the tube. In all 
the eleven glasses tested the conductivity could be 
expressed as the product of a constant into a power of 
the ace centigrade about — 4, into e, the base 
of the Napierian logarithms, to the power — A/T, where 
NO. 2785, VOL. 111] 
NATURE 

: 

S75 
A is a constant and T the temperature centigrade. A 
table of values of the constants for the glasses tested 
is given. 

HEATING IN ELECTRIC ConpucTorS.—An important 
research on the heating of buried cables has just 
been communicated to the Institution of Electrical 
Engineers by Mr. S. W. Melsom and Mr. E. Fawssett. 
Most of the tests were made at the National Physical 
Laboratory, but some were made under actual 
working conditions, the cables being laid in all kinds 
of soils. The rating of a cable depends on the rate at 
which it can dissipate the heat generated in it by the 
electric current, and hence it was necessary to calculate 
what current it could carry under different working 
conditions. Apparently the thermal conductivity of 
the insulating material of the cables does not vary 
appreciably with temperature, and thus the solutions 
of the thermal problems which Fourier gave in his 
“Théorie analytique de la chaleur,’ published in 
1822, apply. The thermal constants of various kinds 
of soil are given, and so by the help of formule the 
maximum permissible currents in the various cases can 
be readily computed. It was found that in certain 
cases existing cables could carry greater currents 
safely, and hence economies can be effected. The 
research, which was a costly one, has taken several 
years, and was carried out on behalf of the British 
Electrical and Allied Research Association. 
A REcORDING SACCHAROMETER FOR BREWING.— 
Messrs. Negretti and Zambra have constructed an 
instrument known as a hydrograph or recording 
saccharometer, which is compensated for tempera- 
ture. It has been designed and constructed to 
provide a simple and practical means of showing and 
recording the specific gravity of wort flowing to the 
under-back, copper, etc. It consists of a cylindrical 
vessel on the lower portion of which is a -in. pipe, 
through which the wort is admitted. To prevent 
eddies in the vessel, an inlet pipe leads into an annular 
ring, which distributes the flow evenly round the 
vessel. A cylinder and copper gauze is also provided 
through which the wort percolates. An outlet pipe 
at the top of the external cylinder is provided, and 
here again there is another annular ring over which 
the wort flows, with the object of preventing eddies. 
Within the inner copper gauze cylinder a hollow float 
of thin nickel heavily coppered is suspended. The 
hollow float is completely filled with the liquid, and is 
connected with the recording instrument by means 
of a chain immediately above the vessel. The chain 
is connected with a grooved quadrant mounted on a 
knife-edged axis. On the opposite side a weight is 
provided to balance the float when it is in the liquid, 
the zero adjustment being provided by an adjustable 
weight. The indications of the instrument are rendered 
independent of temperature from the fact that the 
wort in the cylinder and in the float are at the same 
temperature. The clock carrying the chart revolves 
once in six hours, and the graduated portion of the 
chart is marked from 1ooo to 1100° specific gravity, 
and subdivided to 2° specific gravity, which on the 
chart is equal to #yth of an inch. The pen marks in 
a continuous ink line on the chart, and the readings 
can be made to }° specific gravity with the greatest 
accuracy. In an ordinary mash tun, however, the 
wort from the various taps are often running at 
different temperatures and at a different specific 
gravity, so that the measurements made with the 
wort from one tap will not of necessity give the 
average specific gravity of the whole wort. The 
objection does not apply if the wort is drawn off 
through one spend pipe or is running from the under- 
back to the copper. 
