July 22, 1922] 



NA TURE 



1 29 



The assemblage is attributed to temporary floods 

 sweeping across a surface on which the animals 

 decayed. At several horizons in the Oligocene beds 

 of Indian Creek Basin calcareous algal crusts have 

 accumulated up to a foot in thickness, probably 

 formed by a species of Cyanophyceae. 



Photosynthesis of Nitrogen Compounds. — In 

 a paper published in the June issue of the Journal 

 of the Chemical Society, Prof. E. C. C. Baly, Prof. 

 I. M. Heilbron, and Mr. D. P. Hudson describe the 

 photosynthesis of nitrogen compounds from carbon 

 dioxide and nitrates. It has previously been reported 

 that decisive evidence of the production of form- 

 aldehyde by the action of light on carbon dioxide and 

 water, in the presence of photocatalysts, had been 

 obtained. It is now found that the " activated 

 formaldehyde " so produced can react with potassium 

 nitrate. This reaction takes precedence of the 

 polymerisation of the activated formaldehyde to 

 reducing sugars. When the activated formaldehyde 

 is produced at a rate greater than that at which it 

 can react with the nitrite and with the form- 

 hydroxamic acid thus formed, the excess polymerises 

 to reducing sugars. In this case, the two reac- 

 tions take place simultaneously and independently. 

 Small traces of ammonia are frequently found in the 

 solutions after exposure to light, and activated 

 formaldehyde reacts with ammonia to give methyl- 

 amine. This confirms Pictet's contention that form- 

 aldehyde acts in photosynthesis as a methylating 

 agent. In the synthesis of compounds by the action 

 of activated formaldehyde on formhydroxamic acid, 

 oxygen is set free. The possible modes of formation 

 of indole and quinoline compounds are discussed, 

 and the paper is one which has great interest from 

 the point of view of plant chemistry. 



Iron Ore in South Australia. — The Geological 

 Survey of South Australia has recently published in 

 Bulletin No. 9 a very complete account of the iron 

 ore resources of South Australia by R. L. Jack, 

 Deputy Government Geologist. The iron ores of 

 South Australia are of importance, first of all as a 

 flux in smelting, particularly in smelting the silver- 

 lead ores of Broken Hill ; ultimately Port Pirie 

 became the centre of this lead-smelting industry, and 

 the bulk of the iron ore required was supplied from 

 the important deposit at Iron Knob, which was 

 acquired by the Broken Hill Proprietary Company. 

 Subsequently this company took advantage of the 

 large supply of good iron ore thus available to erect 

 important iron and steel works at Newcastle, New 

 South Wales. These steel works were started in 1915, 

 and the South Australian production of iron ore 

 went up at once from a little more than 37,000 tons 

 to nearly 265,000 tons, while in 1921 it reached nearly 

 629,000 tons. Since 1919 the value of the iron ore 

 produced has exceeded that of any other mineral 

 product. A very large number of deposits of iron 

 ore are described in this Bulletin, though it is obvious 

 that the two groups, Iron Knob and Iron Monarch, 

 with estimated reserves of 133 million tons, and Iron 

 Prince and Iron Baron, with estimated reserves of 

 32 million tons, overshadow all the others in im- 

 portance. Since South Australia possesses no fuel 

 supplies for metallurgical purposes, the iron ore 

 production is necessarily for export, and on this 

 account the accessibility of a deposit of iron ore in 

 South Australia forms an essential element in deter- 

 mining its economic importance ; due regard has been 

 paid to this point in describing the various deposits, 

 stress being laid on those that are well suited for 

 export purposes. 



NO. 2751, VOL. I io] 



Formation of Thunderstorms. — Mr E V 

 Newnham, of the Meteorological Office, has con- 

 tributed a discussion, Professional Notes, No. 20, on 

 the formation of thunderstorms over the British [sles 

 in winter. Thunderstorms are rare in winter over 

 eastern England, but they occur more frequently 

 in the west and north. In January during the eight 

 years discussed, 1900-1907, storms occurred on one 

 or two days only, on the east coast of England but on 

 19 days at Blacksod Point, 14 at Stornoway, and n 

 at Valencia. Forty years ago Dr. Buchan showed 

 that thunderstorms were quite common in winter in 

 the west of Scotland but were very rare in the east 

 The author has attempted to explain the cause of 

 the winter thunderstorms, following the reasoning 

 generally admitted for the formation of thunder- 

 storms m summer, namely, instability of the air with 

 height caused by a rapid fall of temperature. He 

 attributes the instability in winter to the heat 

 imparted to the lower layers of cold air currents in 

 disturbances which have come from cold northern 

 regions and have subsequently travelled over a 

 considerable area of the warmer ocean. Maps are 

 given showing the trajectories of the January storms 

 he has discussed. It is shown that when a thunder- 

 storm occurred with a south-west or west wind the 

 origin of the air was nearly always in higher latitudes, 

 and air which traverses a long stretch of ocean seldom 

 occasions thunderstorms unless it has come from 

 very cold regions, but with these conditions thunder- 

 storms usually occur. 



A Direct-reading Spectrometer. — The Govern- 

 ment Laboratory exhibit at the Royal Society 

 Conversazione on May 17 included a new type of 

 direct-reading spectrometer made by Messrs. Belling- 

 ham and Stanley, Ltd., which embodies several novel 

 features. The optical arrangement is shown in Fig. 

 1. The light entering through the slit 1 is reflected 



by a small right-angle prism on to a concave mirror 

 3, which directs a parallel beam of light on to the 

 dispersing prism 4. The prism reflects the beam 

 back to the concave glass mirror which brings it 

 to a focus in a plane on the slit 1'. The dispersing 

 prism is mounted on a rotating table which may be 

 turned by the arm 5 operated by the micrometer 

 screw 6. The screw head is divided so that it can 

 be set to pass any particular wave-length of light 

 to slit 1', and thus the instrument can be used as a 

 monochromatic illuminator. For investigations in 

 the ultra-violet the glass prism 4 is replaced by one 

 of quartz, and the mirror is of quartz with mercury 

 tinfoil amalgam backing. When in use as an infra- 

 red spectrometer the dispersing prism is of either 

 quartz or rock-salt. The chief advantages of this 

 design are that the 30 prism is always used in the 

 position of minimum deviation, and that with the 

 concave mirror no chromatic differences of focus are 

 introduced. 



