532 



NATURE 



{Oct. 2, 1879 



probably influenced by temperature, pressure, and nature of 

 the base neutralised. Ostwald's researches show that the 

 affinity exerted between an acid and a base may be re- 

 garded as the product of the specific affinity-constants of 

 the acid and of the base ; i.e., as made up of two parts, 

 one of which is dependent on the acid and the other on 

 the base. 



The connection between chemical structure and affinity 

 is touched upon by Ostwald. His numbers show that 

 while the relative affinity of acetic acid is represented by 

 about I "3 (nitric acid = 100), that of monoehloracetic 

 acid is represented by 7, that of dichloracetic acid by 

 33, and that of trichloracetic acid by 80. Similarly, 

 the entrance of oxygen into the molecule of an acid in- 

 creases the affinity, while the addition of CHj decreases 

 the affinity.^ 



The importance of the results, a very short sketch of 

 which I have endeavoured to give, cannot be overlooked. 

 We seem approaching the time when exact knowledge 

 will be obtained of that mysterious force, chemical affi- 

 nity; but before this exact knowledge is attained, much 

 ■work remains to be done. Not the least of the benefits 

 bestowed upon their fellow chemists by the three natu- 

 rahsts whose papers I have mentioned, is that they have 

 directed their attention to a branch of chemical science 

 which, although it presents great difficulties, yet promises 

 results of the most paramount importance to science. 



Cambridge, August M. M. Pattison Muir 



NOTES FROM ICELAND 



DURING the last three weeks the writer has travelled 

 over between four and five hundred miles of country 

 in Iceland, in the course of which various facts have pre- 

 sented themselves which may interest some of the readers 

 of this journal. These " Notes " are necessarily desultory, 

 because the main facts connected with the natural pheno- 

 mena of the country are so well known that the most we 

 can do is to supplement some of them. 



Submarine Eruption off Cape Reykjanes. — The only 

 eruption recorded in Iceland during the present year took 

 place off Cape Reykjanes on May 30, near the Geirfu- 

 glasker island, thirty-two miles from land. It is described 

 by a farmer named GuSmundsson, living near Kirkjuvogr, 

 and his account of it is published in the Heilbrigdistindi 

 for June last. Smoke appeared from the sea on May 30, 

 and on June i it was carried inland by a west wind. For 

 thirteen or fourteen days it w-as difficult to navigate the 

 sea about Reykjanes on account of the smoke, and just 

 before it cleared off, ashes fell on the coast lands. An 

 appearance as of fire was also seen out at sea. This is 

 positively all the information we possess concerning this 

 eruption. It is sufficiently meagre, but the district about 

 Cape Reykjanes is very thinly populated. The road, or 

 track, is carried over a lava-stream, and is one of the 

 worst in Iceland ; the houses are few and far between, 

 and the keeper of the lighthouse told us we were the only 

 visitor he had seen this year. It is probable that volcanic 

 phenomena often pass unnoticed in a country which is so 

 thinly peopled, that with an area one-sixth larger than 

 that of Ireland, the population (72,000) is less than that 

 of Norwich. Submarine eruptions have more than once 

 previously taken place in this district ; small volcanic 

 islands have been raised above the level of the sea, and 

 have sunk again, leaving dangerous reefs. At Cape 

 Reykjanes (hence the name) there are numerous hot 

 springs which deposit silica, and which are therefore of 

 the same nature as the geysirs. The springs rise through 

 beds of highly decomposed tuff; large quantities of steam 

 are emitted, and the soil in the vicinity is so soft that it 

 is necessary to carefully choose one's footing. Pools of 



' The results of Ostwald, and alsj those of Guldberg and Waage, are corro- 

 borative of those obtained by Dr. C. R. A. Wright m a paper pubHshed in 

 the Phil. Miif., December, 1874. 



boiling blue mud (like the maccalube near Girgenti) are 

 also found in the vicinity. 



Craters of the Eruption of Hekla of February, 1878. — 

 Last autumn we gave an account in this journal (vol. xviii. 

 p. 596) of a visit to the scene of the new eruption, which 

 took place about four miles from the principal craters of 

 Hekla at the end of the preceding February. The obser- 

 vations of Herr Nielsens, a merchant of Eyrarbakki, and 

 of Prof Tomas Hallgrimson, were also recorded. The 

 former has just communicated to the writer the result of 

 certain measurements of the principal of the new craters, 

 which he made a few months ago. Three of the craters in 

 the centre of the group were measured. The fonn of the 

 first is that of a funnel, 100 Danish feet ^ in diameter. A 

 good deal of steam issued from the bottom of the crater, 

 and prevented the depth from being accurately determined, 

 but it appears to be about 150 feet. The second crater is 

 of horseshoe form, the straight wall joining the curve of 

 which, is perfectly vertical. The diameter increases as it 

 descends, being at the top about 30 feet, and at the bottom 

 50 ; while the depth is also 50 feet. The third crater is of 

 the shape of a parallelogram, 40 feet long by 30 broad, 

 and 40 feet deep. The walls are perpendicular. No lava 

 issued from the second and third of these craters, but 

 quantities of ash and pumice. The greatest quantity of 

 lava flowed from the most southerly crater nearest to the 

 summit of Hekla. The approach to this is very difficult 

 on account of the extreme jaggedness of the lava. The 

 whole field of new lava appears to be covered with an 

 innumerable quantity of small craters, but a closer exar.ii- 

 nation proves that they have been produced by the molten 

 lava beneath forcing out portions of the upper sohdified 

 crust, at places where snow or water caused the genera- 

 tion of large quantities of steam. Most of the real craters 

 are split in twain, and the sides are lined with incrusta- • 

 tions of common salt. 



A few weeks ago Miss Thora Pjeturssen, of Reykjavik, 

 ascended Hekla, and reports the appearance of steam 

 from one of the main craters ; last year when we ascenc'ed 

 the mountain no trace of steam appeared from any one of^ 

 the three main craters, the most recent of which 

 formed in 1845. Hekla only enters into eruption at let 

 intervals of time. 



Slight shocks of earthquake are common in the south- 

 east districts, in Guldbringu Sysla and Rangarvalla Sysla. 



Climate. — The presence of jokulls covered with per- 

 petual snow ; of the Gulf Stream, and of an arctic currc nt 

 tend to make the climate of Iceland very variable 

 subject to sudden changes. On August 20, when we leP 

 Kalmanstunga, in the centre of the island, the sun Avas 

 as hot as during an English mid-August day ; later in the 

 day as we passed the Geitlands jokull a piercing icy wind 

 bore down upon us with great force, and again towards 

 evening when we entered the northern end of the Thing- 

 vellir valley it was warm and summer-like. During the 

 course of that day we experienced a difference of more 

 than 100" F. Again on August 30, at Eyrarbakki, on the 

 south coast, N. lat. 63° 65', the thermometer at 6. a.m. 

 stood at — 1° R. = 29°75 F., and a crust of ice had 

 formed on all exposed water. At 10 A.M. a bright hot 

 August sun was shining and the air was still. At 3 p.m. 

 rain and violent wind occurred, and towards evening it 

 again cleared up. Frequently the wind drops suddenly, 

 and a complete change of weather may take place in the 

 course of a few hours. The summer has been unusually 

 dry and wann, but on August 31 the weather began to 

 break up. On that day we travelled from Eyrarbakki to 

 Reykjavik by way of Reykir (in Olfusahreppr), and we 

 shall never forget the difficulties of crossing the Hellis- 

 kard, a low spur of the mountain Hengill. The whole 

 tract is either the living palagonite rock, or detached 

 fragments heaped together in confusion. Hence it is 

 only possible to proceed at a slow space. A violent wind 

 .' One Danish foot = I'las Enghsh foot. 



