3 22 



NATURE 



[August 3, 



bum with a flame in an atmosphere of coal-gas the very 

 same phenomena are observed, the hot coal-gas being 

 positive relatively to the air-flame. All these flames 

 showed a potential varying from about \\ to \\ times that 

 of a Daniell's cell. The flame of bisulphide of carbon 

 gave a lower result, and so did a magnesium flame. The 

 introduction of any salt of a metal — such as chloride of 

 potassium — into the flame lowered the potential. 



Moreover when wires of other metals were employed 

 the differences of potential were not the same as before. 

 Whilst the lower electrode of platinum remained, the 

 upper electrode was replaced by a copper wire when the 

 potential rose to 2 Daniell's cells. With aluminium it 

 was equal to 3, and with magnesium to yz Daniell's. 

 Using a lump of clean sodium as electrode the potential 

 even rose to five times the Daniell cell. 



Using as a fluid electrode a drop of water at the end of 

 a capillary tube similar results were obtained, though the 

 differences of potential were smaller. 



These experiments corroborate the suggestion that the 

 flame acts like the acids between the poles of a battery- 

 cell, or that the action is an " electrolytic " one. 



Messrs. Elster and Geitel succeeded in joining elec- 

 trically together the flames of twenty-five spirit-lamps, by 

 the device of causing a curved piece of platinum wire to 

 lead from the base of one flame to the tip of the next, and 

 another piece of wire from the base of this to the tip of 

 the succeeding one, and so on. This "flame-battery" 

 of course had a potential twenty-five times as great as 

 that of one flame. But it would not yield much current, 

 owing to the enormous internal resistance of the flames 

 themselves. 



Another most important series of researches was then 

 undertaken to investigate whether, without any flame or 

 any products of combustion, a difference of potential 

 could be observed between a red-hot platinum wire and a 

 cold platinum wire whose tip was immersed in the cur- 

 rents of heated air that rose from the former. This was 

 accomplished by using as one electrode a thin piatinum 

 wire heated to redness by passing through it the current 

 of a battery. And here, without any flame, a difference 

 of potential of about one and a half of a Daniell's cell 

 was found, the upper electrode being positive, relatively 

 to the glowing one. From this experiment, which was 

 confirmed in a variety of ways, it appears that a flame is 

 not in itself a source of electrification at all. Messrs. 

 Elster and Geitel therefore regard the electrification as a 

 thermo-electric phenomenon ; though they use this term 

 in a slightly different sense from that in which it is used 

 in the text-books. 



They conclude, therefore, that the production of elec- 

 trification by flames is (\) independent of the size of the 

 flame ; (2) dependent on the nature and state of surface 

 of the electrodes ; (3) dependent on the nature of the 

 gases that are burning in the flame ; and (4) dependent 

 on the state of ignition of the electrodes. 



They therefore regard Pouillet's theory as being wrong, 

 whilst the theories of Matteucci (and Hankel) and of 

 Buff are both, so far as they go, correct. If this so-called 

 thermo-electric origin of the electrification be the true 

 one it is a very important fact indeed ; and, as these able 

 experimenters say, will probably explain the back-electro- 

 motive force which is observed in the voltaic arc. This 

 is not the least interesting point in this very interesting 

 research. S. P. T. 



THE METEOROLOGY OF ICELAND DURING 



THE WINTER AND SPRING OF 1881-82 

 'TPHE observations made last winter by Mr. Thorlacius, 

 *■ observer for the Scottish Meteorological Society at 

 Stykkisholm, Iceland, have been received by the Society, 

 and they are of the greatest interest in connection with the 

 unexampled mild weather which prevailed in this country 



for the five months ending March. The mean pressures, for 

 these five months, at 32 and sea level, were respectively 

 29/201, 29-140, 29-295, 29-471, and 29-258 inches, the mean 

 of these months being thus only 29-273 inches. In Lon- 

 don the mean of the same months was 30-123 inches, or 

 0-850 inch higher than that of Stykkisholm. The means 

 for these two places for the twenty-four years ending with 

 1880 are for London 29-948 inches, and Stykkisholm 

 29-552 inches, the difference being 0-396 inch, or less than 

 half the difference during the winter of 1881-S2. The 

 greatest difference occured in January, the mean pressure 

 for which month in London was 30365 inches, and at 

 Stykkisholm 29-295 inches. Pressure in the north-west of 

 Iceland was thus 1-070 inch less than in London. 



On January 14 the pressure at Greenwich was 30.572 

 inches, and the maximum temperature 42°'4, but at Styk- 

 kisholm on the same day temperature rose to 46"5, with 

 a storm of wind from the south, and pressure was as low 

 as 2S-290 inches, being 2-282 inches lower than at Green- 

 wich. At Greenwich pressure rose at 10 a.m. of the 18th 

 to 30-973 inches, the maximum temperature being 34-2 ; 

 but at Stykkisholm pressure on the same day was only 

 29466 inches, the maximum temperature rose to 46 0- 5, 

 and a storm of great violence from the south set in at 

 noon and lasted till 6 a.m. of the following day. 



During the five months of high temperature in the 

 British Islands the following winds prevailed less than 

 the average of previous years, viz. W. 4, X. 1, X.E. 6, 

 and E. S days ; but winds from S.E. were 2, S. 7, and 

 S.W. 14 days above the average. Hence during the 

 winter of 1 88 1-82 atmospheric pressure was not only much 

 under the mean in the north-west of Iceland, but the 

 great depression, which is one of the most prominent fea- 

 tures of the meteorology of the northern hemisphere in 

 the winter months, was, as indicated by 21 days' greater 

 prevalence of S. and S.W. winds, situated considerably 

 to the north-west of its usual position. Very low mean 

 pressures for the winter months are of frequent occur- 

 rence in Iceland, but it is seldom that they continue un- 

 interruptedly low for five months in succession. Thus, 

 since Mr. Thorlacius began his observations in 1845, 

 mean pressure was nearly as low only on three other 

 winters, viz., the winters of 1847-4S, 1850-51, and 1S62-63, 

 when the mean pressures of these five months were 

 respectively 29-308, 29-330, and 29-310 inches. 



The weather underwent a complete change about the 

 middle of March, when S. and S.W. winds nearly ceased 

 and a high mean atmospheric pressure ruled, with re- 

 peated cyclonic disturbances passing to the southward of 

 Stykkisholm, and involving Iceland in a succession of 

 violent north-easterly storms of wind, which broke up the 

 Arctic ice to the north, drove it southward, and stranded 

 it on the north and east shores of the island. In these 

 circumstances the weather became unusually inclement 

 and unseasonable, and Mr. Thorlacius reports that no 

 equally severe and disastrous spring has occurred there 

 within the memory of any one living. About Easter all 

 the food for horses, sheep, and cattle had been used up, 

 and these animals died in great numbers. In his parish 

 alone, 62 horses, 1700 sheep and swine, and 7 cows 

 perished, causing a direct loss of 1220/., and the popula- 

 tion has been brought face to face with a serious famine. 



Though the Government is taking every measure in its 

 power to mitigate the calamity, the prospect is most 

 gloomy. Besides this, all, or nearly all, of the lambs 

 have died, and owing to the great cold and want of rain, 

 grass has scarcely yet begun to grow, the sea-ice still 

 (July 1) surrounds the entire north and east of the island 

 in immense masses, and no ship can get through it to 

 any of the harbours of these coasts. On the north coast 

 the ice drove ashore about fifty large whales, of which 

 the smallest is said to be forty-five feet in length, which 

 proved an unexpected relief to the poor peasantry, and 

 even to the proprietors of the coast districts. 



