Dec. 1 6, 1886] 



NA TURE 



147 



one of the earliest workers in volumetric analysis; in 

 1827 he devised a method of valuing bleaching-powder 

 and bichrome by means of standard solutions. His specu- 

 lations on the nature of white indigo, on the constitution 

 of bleaching-powder, and on the ferrocyanides and nitro- 

 prussides were much in advance of his day. His theory 

 of catalysis, which he illustrated by many striking and 

 original examples, was extended by Playfair, and has 

 been subsequently worked out by Kekule as the only 

 satisfactory explanation yet given of a very remarkable 

 and interesting group of phenomena. Graham's early 

 experiments on the heat of chemical combination and the 

 nature of solution induced Mercer to test the practica- 

 bility of effecting the partial separation of different 

 hydrates by some process of fractional filtration. These 

 experiments, made from a purely scientific stand-point, 

 resulted in the discovery of the mode of action of the 

 caustic alkalies on cellulose, and led to the process which 

 has come to be known as " mercerising," in which cotton 

 fabrics are " fulled " by their contraction on treatment 

 with caustic soda. Mercer appears to have been the first 

 to notice the remarkable solvent action of an ammoniacal 

 copper solution on cotton, which could be re-precipitated 

 as almost pure cellulose by the addition of an acid. His 

 habit of searching for first principles led him, as far back 

 as 1854, to speculate on the relations among the atomic 

 weights of the chemical elements, and the constitution of 

 chemical compounds : he brought his views before the 

 Leeds meeting of the British Association in 1858. He 

 was an early worker on photography, and devised several 

 modifications of the cyanotype process adapted to printing 

 on cambric and similar fabrics. 



Mercer was one of the original Fellows of the Chem- 

 ical Society, and he was a juror of the Exhibitions of 

 1 85 1 and 1862. In 1852 he was elected into the Royal 

 Society. He died, ripe in years and rich in the content- 

 ment afforded by the retrospect of a well-spent life, on 

 November 30, 1S66. T. E. Thorpe 



THE BRITISH INTERNATIONAL POLAR 

 EXPEDITION 



Observatio7is of /he Iniemational Polar Expeditions, 



1882-83 : Fort Rae. 326 pp. 4to, and 29 plates. 



(London : Triibner and Co., 1886.) 

 A T the Polar Conference of Vienna in April 1SS4 it 

 •^ »■ was declared to be very desirable that the results 

 from all the circumpolar stations' should be published by 

 Christmas 1S85. This time was not kept strictly by any 

 of the parties. The first Report completed was that of 

 Lieut. P. H. Ray, of the U.S. Army, for Point Barrow, 

 which appeared early in 1886, and this has now been 

 followed by the present volume, which came out in 

 August last. 



The other Expeditions, however, have not been idle, for 

 several have issued portions of their Reports : e.g. the 

 French for Cape Horn ; the Russians for Sagastyr at 

 the mouth of the Lena ; and the Austrians for Jan Mayen ; 

 while quite recently the Germans have announced 

 the publication of the results for their two stations — 

 Cumberland Sound and South Georgia. 



The British Expedition was from the outset at a serious 



disadvantage. It was not until April 2, 1S82, that the 

 definite sanction of the Government was obtained, and 

 the party were obliged to sail from Liverpool on May 1 1 

 in order to catch the Hudson Bay Company's convoy 

 from Winnipeg. Accordingly the time available for pre- 

 parations and training was extremely short, and no 

 special instruments could be made. 



The party consisted of Captain (now Major) H. P. 

 Dawson, R..\., with two sergeants and a gunner of the 

 same service. The journey was prolonged and fatiguing, 

 lasting three months and a half, and the Expedition only 

 reached its destination at 10 p.m. on August 30. Only 

 one day was thus available for unpacking, &c., before the 

 regular hourly observations commenced. 



The start for the return journey was made within three 

 hours of the time of the final observation, and even then 

 it was only owing to a fortunate shift of wind on Lake 

 Athabasca, which opened the ice and allowed the boats to 

 get through, that the party was able to reach Manitoba, 

 with its baggage, in October. Otherwise the instruments 

 must have been left behind for some months, as the 

 Expedition must have completed its journey by sledge. 



The observations have been discussed in strict accord- 

 ance with the International scheme, the units employed 

 being metric and centigrade. The magnetic discussions 

 were carried out by Major Dawson in conjunction with 

 Mr. Whipple. The meteorological work was intrusted to 

 Mr. R. Strachan and Mr. John A. Cuitis, of the Meteoro- 

 logical Office. 



The magnetic observations are specially interesting, 

 from the proximity of the station to the magnetic pole 

 The disturbances were therefore of great frequency and 

 violence, as will be seen from the plates to the volume. 

 The auroral journal also aftbrds a copious store of infor- 

 mation on that sitbject. 



The following few results, which we extract from the 

 observations made by the Expedition, will be of interest 

 to our readers : — 



The barometer at Fort Rae varied between 771 mm. 

 (30-35 inches) and 721 mm. (28-39 inches), with a maxi- 

 mum daily range of 24 mm. (0-94 inch), and the least of 

 0-7 mm. (0-03 inch). 



The highest thermometer-reading recorded by the Ex- 

 pedition was 25°-6 C. (78°-! F.), whilst the lowest was 

 - 44°-6 C. (— 48°-3 F.) in the air, the terrestrial radiation 

 instrument registering - 46°-^ C. (- 52°-! F.). 



On the coldest day experienced (January 3) the mean 

 temperature of the twenty-four hours was - 4i°'9 C. 

 (- 43 '4 F-), whilst that determined for the hottest day^ 

 (August 13) was i9''-9 C. (67°-S F.), giving an extreme 

 range of average daily temperature of 6l°-S C. (iii°-2 F.). 



The highest mean velocity of the wind recorded any 

 day was 8'5 metres per second (19 miles per hour) from 

 the north north-west. 



The average magnetic declination at Fort Rae was 

 40° 20' E., the extreme change observed in the diurnal 

 range being 11° 25'. On the most quiescent day the 

 angular motion of the needle was 0° 17', both values- 

 largely exceeding movements observed in these latitudes. 



The dip or inclination of the needle was 82° 55', 

 whilst the measured values of the total and horizontal 

 magnetic forces were 0-62 and o-o8 electrical units 

 respectively. 



