August 21, 1919] 



NATURE 



491 



Under the heading of "The Freedom of the Skies " 

 the Scientific American for July 26 has- an article by 

 Prof. McAdie which deals with " some of, the problems 

 that will have to be solved as the human race takes 

 to the air.'' Much that is said is reasoned from 

 the analogy of the 'freedom of the seas." The recent 

 great war has full\- shown the value of a command 

 of the sea or air. The word " overcloud " is proposed 

 for association and definition with "oversea" ^nd 

 "overland." It is suggested that what the Gulf 

 Stream and the Japan Current are to the mariner 

 the prevailing westerlies are to the aviator. The 

 trades and monsoons are likened to rivers at the 

 ground surface. It is stated that "the war just ended 

 exemplified for the first time in history the right of a 

 neutral nation to claim as territory the air above." 

 The author deals with many features of interest, and 

 the article contains much that is suggestive; one 

 such point is that "if a steamship meets an adverse 

 tide, her progress is delayed just so much, depending 

 on the strength of the current ; whereas when an air- 

 ship encounters strong head winds, her pilot can rise 

 or fall below the level of that particular air current 

 and find a level in which the air will be moving with 

 him and not against him." Many of the analogies 

 dealt with show the great advantage of the combined 

 association of mathematics and meteorolog\- for a 

 proper study of the upper air. 



Monthly meteorological charts, which are issued 

 by the Meteorological Office both for' the North 

 Atlantic and East Indian seas, are primarily intended 

 for seamen. Now that aircraft are becoming of such 

 importance, especially considering the rapid strides 

 made in the last few months and the prospective 

 voyage to India of R 33, these meteorological charts 

 are assuming much greater interest. The Atlantic 

 chart for the present month contains a large amount of 

 valuable information. At present the North Atlantic 

 is the ocean of primary importance for aircraft, but 

 the winds are dealt with in a less satisfactory manner 

 than for other oceans, "the frequency, the direction, 

 and the average force of some characteristic winds 

 are shown," whilst fuller details and greater precision 

 are essential. A track is given showing the mean 

 path of centres of cyclonic areas between America and 

 Europe in August for the years 1883-91. A longer 

 period, embracing the storms of recent years, would 

 enhance the value of this information, appending, if 

 practicable, details of individual instances. In August 

 the south-east trade is seen to extend considerably to 

 the northward of the equator, reaching on the eastern 

 side so far north as latitude 13° N. The frequency 

 of cloud with various winds at different times of day 

 is given for Valencia and for St. Johns, Newfound- 

 land, at the back of the chart. The August chart 

 for the East Indian seas shows that the south-west 

 monsoon is predominant over the sea to the north of 

 the equator, whilst south of the equator to 25° S. the 

 south-east trade blows almost uninterruptedly. North- 

 westerlv winds predominate over the whole length of 

 the Red Sea. In August the average barometric pres- 

 sure in the Red Sea is lower than in any month of 

 the vear, and the average air temperature is the 

 highest of the twelve monthly values. 



In the Journal of the Royal Society of Arts for 

 June 20 Mr. Watson Smith' directs attention to a 

 theory recently advanced by Tschirch to account for 

 the spontaneous combustion of haystacks. It is 

 based upon observations made in the drying of medi- 

 cinal plants. A first phase of heating is regarded as 

 due to oxidation processes caused by the plant 

 Oxvdases at the expense of the air present in the stack. 

 This results in a small rise of temperature, which 

 NO. 2599, VOL. 103] 



ceases when the oxygen of the air in the stack is 

 exhausted. In the next phase the chief role is played 

 by reductases, which act energetically between 50° and 

 70° C, deoxidising and eventually carbonising such 

 substances as amino-acids and carbohydrates. The 

 danger of ignition lies in the accumulation of oxygen 

 withdrawn by the reductases; the actual reduction 

 processes would not themselves produce sufficient heat 

 to ignite the material. To obviate the risk of 

 spontaneous combustion two precautions are recom- 

 mended : — (i) A thorough drying of the hay before 

 stacking, which minimises enzyme action, and 

 (2) thorough aeration of the stacks, which may be 

 secured by building them in layers with air spaces 

 between. 



The forty-third annual report of his Majesty's 

 Inspectors of Explosives (1918) (Cd. 278, 1919) is of 

 particular interest by reason of the inclusion of 

 approximate figures for the production of explosives 

 and ammunition of all classes in this country for the 

 whole period from the outbreak of war to the signing 

 of the armistice, together with statistics of the acci- 

 dents which occurred. Of the three chief classes of 

 military explosives the outputs and casualties were : — 

 (i) Ballistites and cordites, 181,712 tons; persons 

 killed, 35; injured, 50 (of the killed 27 lost their lives 

 in one accident). (2) Picric acid, T.N.T., and other 

 coal-tar products, 107,713 tons; killed, 177; injured, 

 368. (3) Other nitro-compounds, 62,048 tons; killed, 

 31; injured, 91. In all there were 1277 accidents 

 reported, and in 544 no personal injury was caused. 

 The maximum number of persons employed was 

 86,555; the average, 61,808. The tota? loss of life 

 was 325, with 13 16 injured, giving 1-25 killed per 

 1000 and 5 injured, compared with a fatality rate of 

 I per 1000 for the five-year period ending 19 10. The 

 inspectors are more than justified in their comment 

 that, " having regard to the output pro<luced at high 

 pressure, largely by workers with no previous experi- 

 ence, supervised in many cases by equally inexperi- 

 enced officials, the general result may be regarded as 

 satisfactory." It is a remarkable testimony to the 

 supervision and protection of the workers that in filling 

 more than 8,374,000,000 small-arm cartridges and 

 83,600,000 hand grenades in licensed factories during 

 the war period there was not a single fatal accident 

 and only 48 workers injured, with one exception all 

 being engaged on cartridges. Nor was there any 

 loss of life in the manufacture of blasting explosives 

 (other than gunpowder) or in the conveyance of ex- 

 plosives during the year 1918. The report lays special 

 stress on the dangers of compositions containing 

 aluminium powder, for, although such mixtures are 

 not unduly sensitive during test, accidents have been 

 somewhat frequent, the reason oiF the primary ignition 

 being obscure 



When a photographic negative is treated with a 

 solution of a chromate well acidified with hydrochloric 

 acid, the silver of the image is converted into silver 

 chloride, and subsequent application of a developer 

 reduces the silver chloride and leaves the metallic 

 silver much as it was. But if the acid is 

 deficient in quantity, reduction products of the 

 chromate remain and reinforce the image. This 

 method of intensification is well known. In the 

 British Journal of Photography for August 8 Messrs. 

 Lumiere and Seyewetz state that they find that the 

 acidifietl chromate may be replaced by a solution of 

 potassium chlorochromate, thus using a definite sub- 

 stance instead of an indefinite or adjustable mixture. 

 Thev find, too. that if the process is repeated on the 

 same negative, the effect gradually diminishes, and 

 after five or six treatments the intensification becomes 



