Feb. 24, 1 88 1 J 



NATURE 



38: 



M. Coulier made experiments with the products of combustion 

 from flames in which the combustion v\'as as perfect as possible. 

 He found these gases much more active than the air of the room. 

 This he attributed to part'.cle-s of uncoi sumed carbon. He also 

 found the air after rain and storms to te less active, and the air 

 in summer less active than in v\ inter. After extending the experi- 

 ments to alcohol and benzine, the faper concludes with some 

 remarks on the peculiar action of ozone. 



Up to this point the two investigations run perfectly parallel, 

 and the strange lil<eness between the two sets of experiments is 

 not the least interesting point connected with theui. After 

 going over this first paper by M. Coulier, I found he had com- 

 municated a second paper, which will al.-o be found in the same 

 volume of Xhe /oiirnal de P/iarinacic el Jc Chimic, at page 254. 

 This second paper is almost entirely occupied willi a description 

 of some experiments in which inactive air was heated and 

 rendered active. 



In the first experiment described in M. Coulier's second 

 paper a platinum wire was heated in the purified air of the 

 flask, after which the air was active. In the second experi- 

 ment pure air in which hydrogen was burned became 

 active. In the third experiment pure air wlrich was passed 

 through a glass tube surrounded with tinsel ("clinquant"), 

 and moderately heated, was made active. Fourth experiment, 

 oxygen, nitrogen, and liydrogen became active after they had 

 been heated in a tube. After describing tome effects in ventila- 

 tion when Inghly heated air is used, he says, " In the preceding 

 note (the fir-t paper) I believed I could attribute the activity of 

 the air to the presence of solid bodies, and it seemed to me that 

 the only solid body that could escape from a carb'm flame could 

 be nothing but carbon it-elf. It was the remarkable experiment, 

 so easily made, of filtering air through cotton- wool, that led me 

 to forai this hypothesis, which the exjieriments above t elated 

 invalidate (a faire cette hypothese, que les experiences relatees 

 plus haut infirment)." He concludes by saying, "The explana- 

 tion of these phenomena remains still to be found." 



Experiments exactly corresponding to some of those described, 

 in M. Coulier's second paper will be found in mine. Wishing 

 to te.^t the effect of combustion on air, I first made experi- 

 ments to test the effect of heat on the apparatus to be used in 

 collecting the hot gases. For this purpose I passed filtered air 

 through a heated glass tube, after which I found it was remark- 

 ably active. It was found however that this activity is not due, 

 as M. Coulier feeraed to suppose, to the healing of the air, but 

 to ini])urities driven off the surface of the tube by the heat. 

 This was proved by showing that the air remained inactive 

 when the hot tuLe through which it was p.as-ed was thoroughly 

 cleansed. 



In making experiments on the effect of burning gas I arranged 

 a platinum wire, connected w ith a battery, to enable me to light 

 the gas in the pure air of the receiver. On testing the action 

 of the heated wire alone, it was found that simply heating the 

 wire gave ri;e to cloudiness. It was however found that by 

 highly heating the wire its activity was destroyed, all impuri- 

 ties being driven off. 



These experiments explain iVI. Coulier's first and third experi- 

 ments. The fourth experiment is also to be explained by the 

 nuclei driven off the tube by the heat. These nuclei may be 

 driven off in the solid state, or as gases which condense without 

 nuclei « ben highly supersaturated on being cooled to the tempe- 

 rature of the flask. The nuclei are in some ca>es formed by 

 chemicil union of the gases driven off by the heat, and in other 

 ways unnecessary to enter upon here. As to the second experi- 

 ment, more information is required as to arrangement of appa- 

 ratus, &c., before any opinion can be formed as to the origin of 

 the nuclei. 



It now appears to me that this second paper explains why the 

 first results of M. Coulier, though repeated and confirmed by 

 M. Mascart, have not received that general acceptance we.'hould 

 have expected. In his second paper he describes a number of 

 results which he did not succeed in fitting into his hypothesis. 

 They even seemed to him to shake his first conclusions, and the 

 uncertain sound given by his second paper seems to have blighted 

 any fruit his first paper was likely to have produced. There can 

 however be no doubt that M. Coulier was the first to show the 

 important pait played by dust in the cloudy condensation of the 

 vapour in ai«-, and his first paper clearly explains its action. It 

 seems highly probable that if it had not been followed hy his 

 second paper, or if he had succeeded in getting the key to the 

 explanation of his experiments, and his conclusions had con- 



firmed instead of weakening the tenching of his first paper, his 

 result would long ere now have been applied to explain the 

 different causes and the different forms of cloudy condensation 

 in our atmosphere, as well as other physical phenomena. 

 Darroch, Falkirk, February 15 John Aitken 



Geological Climates 



I DESIRE to express my thanks to Dr. John Rae for the 

 valuable contribution of "facts" which he "has added to this 

 interesting question, of which I hope to make use in due time. 



I wish also to answer the question asked by Prof. Woeikoff in 

 his letter of February 17. My authority for January, July, and 

 mean temperatures in the northern hemisphere and in the 

 southern is the mo.-t recent and accurate available, viz.. United 

 States Coast Survey, "Meteorological Researches for the use of 

 the Coast Pilot," P.art i, by William Ferrel (Washington, 1S77). 

 Mr. Ferrel gives the January and July temperatures for every ten 

 degrees of longitude and latitude, up to 80° N. and 60° S. as 

 follows, so far as regards the annual means : — 



Lat. N. 



Annual. 



D ... So-i F. 

 10 ... Sfo ,, 

 20 ... 77-6 ,, 

 30 ... 67-6 „ 

 40 •• 56'5 ,. 



5° ■■ 43'4 .. 



60 ... 29'3 ,, 

 70 ... 14-4 „ 



80 ... 4-5 „ ... 80 ... — 



This table fully justifies what I said of the southern hemisphere 

 as compared with the northern, and is, of course, explained by 

 the existence of three gi-eat gulf streams in the south, which 

 raise the mean temperature, producing insular climates with a 

 small range from July to January. 



Mr. Ferrel adds, at the close of his discussion (p. 22) : — 

 "From Dove's Charts of Isothermal Lines, which do not ex- 

 tend beyond the middle latitudes in the southern hemisphere, it 

 has been inferred that the southern hemisphere is colder than the 

 northern, and this has been the accepted view ever since his 

 charts were first published, in the year 1S52; but from the re- 

 sults obtained above it is seen that the mean temperature of the 

 southern hemisphere is the gi'eater of the two." 



I was well aware that the eat coast of Asia is colder, latitude 

 for latitude, than the east coast of North America, but this has 

 nothing to do with reducing the temperatures of the east coast 

 of America, by means of alterations in the ocean currents of the 

 North Atlantic, which I deny to be possible. 



Samuel Haughton 

 Trinity College, Dublin, February 19 



Climate of Vancouver Island 



As questions connected with the climate of Vancouver Island 

 and the influence on it of ocean currents have lately been the 

 subject of several communications in the pages of Nature, it 

 may be worth while to draw attention to the fact that Esquimalt, 

 at the southern extremity of the island, 'together with several 

 places on the mainhind of British Columbia, have now been for 

 a number of years occupied as regular stations of the Canadian 

 Meteorological Service, and that trustworthy meteorological 

 results are to be found in the annual reports to Government. 



When writing a report on British Columbia for the Canadian 

 Pacific Railway Survey in 1877, I applied to Prof. Kingston, 

 then in charge of the Meteorological Department, for some 

 information on climate, and received from him an abstract, 

 which was published at the time ("Can. Pacific Ry. Report, 1877," 

 p. 246), by which it appears that the mean summer temperature 

 of Esquimalt is 57""82 F., mean winter temperature 34°'4S> 

 mean annual temperature 47°"97. This does not include how- 

 ever the additional results of the last few years. 



Much information on the climate of the northern part of the 

 north-west coast may also be found in the Alaska Coast Pilot, 

 1869, and the U.S. Pacific Coast Pilot, Appendix :, 1S79. ^ In 

 the latter, series of monthly and mean annual isothermal lines 

 are given for the air and sea surface, vi hich — though the observa- 

 tions at command are by no means complete— are doubtless 

 nearly correct. A partial abstract of these, with some discussion 



