400 



NATURE 



[June 19, 19^ 



reception by means of this same bedstead as the 

 antenna to anyone interested. 



Benjamin S. T. Wallace. 

 113 St. James Road, Upper Tooting - , 



London, S.W., June 16. 



Sub-Red Crag Flint Implements and the Ipswich 

 Skeleton. 



I would like Mr. Sutcliffe to read p. 199 of vol. i., 

 part ii., Proceedings East Anglian Prehistoric 

 Society, which contains the original description of 

 the discovery of the Ipswich man. I think it would 

 have been better if he had done this before publicly 

 accusing me of inconsistency in regard to this matter. 



J. Reid Moir. 



THE OXYGEN CONTENT OF THE 

 ATMOSPHERE. 1 

 'PHIS memoir, published under the auspices 

 of the Carnegie Institution of Washing- 

 ton, is of a type with which we are becoming' 

 increasingly familiar — a publication, in fact, 

 which, it may be argued, the institution was 

 created largely to undertake. None of the regu- 

 larly constituted scientific societies would probably 

 charge themselves with the issue of such a work, 

 and it is very unlikely that it would see the light 

 if left to private enterprise. Nevertheless, it is 

 an eminently useful work, and will be welcomed 

 by chemists, meteorologists, and physiologists 

 alike. 



The work is divided into two parts. Part i. is 

 wholly concerned with an historical account of 

 the development of the methods for determining 

 oxygen, in which practically everything contained 

 in the literature has been put together and collated, 

 from the days of Scheele and Priestley to those 

 of Regnault and Bunsen, von Jolly and Morley, 

 down to the methods of our own time depending 

 upon purely absorptiometry processes. Naturally 

 there is nothing very original in this section, and it 

 is well-trodden ground to all who are familiar with 

 the development of eudiometry. It is, however, 

 an interesting and useful compilation, and will 

 be of service to those who are concerned with 

 accurate gasometric analysis, especially in re- 

 lation to the atmosphere, or who desire to know all 

 there is to know relating to its history. 



The second and more immediately important 

 part deals with the experimental work of the 

 nutrition laboratory of the Carnegie Institution, 

 Washington, of which Prof. Benedict is the 

 director. 



For some time past the nutrition laboratory has 

 been engaged, among other things, in an elabor- 

 ate inquiry into the nature of respiratory exchange 

 in relation to metabolic processes, and the neces- 

 sary instrumental equipment has now been brought 

 to a very high degree of precision. After a care- 

 ful investigation into the merits of the various 

 types of modern absorptiometric apparatus, it was 

 decided that the arrangement devised by Dr. Klas 

 Sonden, of Stockholm, a development of the 

 apparatus originally contrived some years ago by 



' The Composition ol the Atmosphere, with Special Reference to its 

 Oxygen Content." By F. G. Benedict. Pp. iii+115. (Washington. D.C. : 

 arnegie Institution of Washington, tqiz ) 



NO. 22/7, VOL - 9 1 ] 



Prof. Pettersson, more fully fulfilled the essential 

 conditions of expedition, convenience and accuracy 

 than any other existing form ; and part ii. 

 is practically made up of a description of the 

 Sonden air-analysis apparatus, illustrated by 

 photographs and woodcuts, together with an 

 account of the plan and methods of research to 

 be undertaken by it, with the results which have 

 been obtained up to the date of publication of 

 the report. 



The principle of the apparatus is essentially that 

 of the original Pettersson instrument, in which the 

 absorption and determination of the carbon dioxide 

 and oxygen are made, as in the Hempel, Orsat, 

 and Haldane arrangments, by means of caustic 

 potash and alkaline pyrogallate, but with the use 

 of water-jackets and compensating pipettes so as 

 to ensure much greater accuracy of reading. 



The plan of the research involved (1) the estima- 

 tion of the comparative oxygen-content of un- 

 contaminated outdoor air under all conditions as 

 to wind direction and strength, temperature, cloud 

 formation, barometer and weather, including rain, 

 snow, fog and mist ; (2) a study of the influence 

 of the temperature of the reagent upon its absorp- 

 tive power; (3) an examination of the air over 

 the North Atlantic Ocean ; (4) on the summit of 

 Pike's Peak; (5) in the crowded streets of Boston 

 and in the subways of New York and Boston. 



Such a programme necessitated a very large 

 amount of experimental work and the analysis of 

 many hundred samples of air. In addition, a 

 large volume of work was needed in control and 

 verification, and especially in tracking down and 

 eliminating sources of possible error. Eventually 

 a routine method was established, and from a long 

 series of determinations it would appear that, as 

 regards oxygen content of outdoor air, no material 

 fluctuation could be detected over a period extend- 

 ing from April, 191 1, to January, 1912. This con- 

 stancy was maintained in spite of all possible 

 alteration in weather conditions, barometric or 

 thermometric changes, or changes in humidity, 

 wind direction, and strength ; furthermore, the 

 experiments were made before, during, and after 

 the vegetative season. The average result of 212 

 analyses showed C031 per cent, of carbon dioxide 

 and 2o'952 per cent (corrected) of oxygen. Hence 

 Dr. Benedict concludes " that air is a physical 

 mixture with the definiteness of composition of a 

 chemical compound." We have, in fact, got back 

 to the position maintained by Cavendish in 

 1783 and by de Marli in 1787, that is, of the 

 uniform constancy of the composition of normal 

 atmospheric air, so far as regards its oxygen 

 content. 



Prof. Benedict further concludes that — 



While the combustion of fuel and the vital processes 

 of men and animals result in a local increase in carbon 

 dioxide and decrease in oxygen on the one hand, and 

 vegetable growth results in a decrease in carbon 

 dioxide and increase in oxygen on the other, the 

 extraordinary rapidity with which the local variations 

 in the composition of the air are equalised is accen- 

 tuated by the observations on street air, which show 

 i but the slightest trace of an oxygen deficit. 



