300 



NATURE 



[Jan. 24, 1889 



■instruction in science may be brought into close harmony with 

 -educational methods employed in other subjects of school 

 teaching. 



Messrs. Macmillan and Co. will also issue soon "Hydro- 

 statics for Heginners," by F. W. Sanderson. The work is based 

 on the author's experience in teaching physics to large classes of 

 boys varying from 12 to 19, and in arranging and conducting 

 •each class in laboratory work. 



A NEW compound, containing aluminium in a lower state of 

 oxidation corresponding to ferrous iron, has been obtained by 

 Prof. Hampe-Clausthal. It is a double fluoride of sodium and 

 aluminium of the composition 2NaF . AlFo. In the earlier 

 experiments which resulted in the production of this interesting 

 substance, cryolite, the natural fluoride of sodium and aluminic 

 aluminium, 6NaF . AljFg, was fused for several hours in a gas- 

 carbon crucible along with a quantity of metallic aluminium. 

 Air was rigidly excluded during the fusion, a current of hydrogen 

 being led through the crucible by means of tubes inserted 

 through the air-tight cover. The carbon crucible was protected 

 from the direct flame of the furnace by means of an outer one o 

 platinum. Under these circumstances the metal dissolved 

 either wholly or in part, depending upon the amount present, 

 in the melted cryolite; a little carbide of aluminium was 

 at the same time formed and disseminated throughout the mass, 

 especially aggregating near the surface, in minute particles, 

 accompanied by small globules of the metal itself. After separa- 

 tion of these particles by various means as completely as 

 possible, it was found that about half as much aluminium had 

 entered into combination as that originally contained in the 

 cryolite, indicating the probability of the course of the reaction 

 being as follows : 6NaF , Al^Fg + Al = 3(2NaF . AIF2). 

 It was afterwards found, however, that by substituting a 

 polished wrought -iron crucible for the carbon one, a product 

 was obtained perfectly free from these particles, carbide of 

 aluminium being no longer a possible product of the reaction, 

 and the excess of metallic aluminium forming an alloy with the iron 

 upon the walls of the crucible above the fused fluoride. Hydrogen 

 was led through as before in order to exclude oxygen. 58 grammes 

 of cryolite were fused for 5^ hours with 29 '5 grammes of the metal ; 

 at the end of the operation the homogeneous white substance 

 formed at the bottom of the crucible on cooling was submitted to 

 -analysis, with results which entirely confirm the above supposi- 

 tion, the numbers corresponding to the formula 2NaF . AlF,. The 

 new compound, which in outward appearance very much re- 

 sembles cryolite, must therefore be considered as sodium alumini- 

 ous fluoride. It may be remarked that all three elements were 

 estimated, the sodium and aluminium in the ordinary manner, as 

 chloride and hydrate, while the fluorine, which was found most 

 •difficult to determine satisfactorily and required prolonged treat- 

 ment, was eventually weighed in the form of calcium fluoride. 

 Now that an aluminious salt has at last been obtained, it is to be 

 hoped that further attempts may follow, having for their object 

 the formation of other compounds corresponding to the well- 

 known salts of ferrous iron. 



Referring to the discovery, last year, at Sandnaes, near 

 Stavanger, in Norway, of enormous deposits of infusorial earth, 

 at the time communicated by Lord Salisbury to the Royal 

 Society, Prof. P. Waage, the well-known Norwegian chemist, 

 is of opinion that this earth should be suitable for the preserva- 

 tion of food, after having been subjected to a process of intense 

 heating, whereby all organic matter should be destroyed. Prof. 

 Waage thinks that sterilized infusorial earth would be very 

 -much better as a means of preservation than boric acid, &c., 

 now used in the preservation of fish. 



Last autumn, a family of the hazel-mouse, Myoxiis avellan- 

 .arius, was discovered in a wood at Slagelse, in Denmark. It is 



said that the animal had never Lefoie been found in that country. 

 The mice had made their nest — ball-shaped in appearai.ee — of 

 grass iind leaves between the branches of a tree, 6 feet above 

 the ground. It had a circular entrance-hole at the side. Two 

 of the animals are now hibernating in the possession of a 

 farmer. 



The Museum of the Chrisliania University has just been 

 enriched with a Runic stone, hitherto unknown, found in the 

 Romsdal. The writing is in older Runic characters, and very 

 clear, but pare of the stone is missing. It is believed to have 

 been a memorial stone. Some years ago, a similar stone was 

 found in the same locality, but the Runes are illegible. 



Thanks to strict preservation, and to the fact that the in- 

 habitants are realizing the value of the bird, the eider has 

 greatly increased in number in Iceland during recent years. 

 The people do all in their power to attract the bird to their 

 property. Among these attractions are bells worked by the 

 wind or by water, the hanging up of dress material of a glaring 

 colour, and the keeping of brightly-coloured fowls. A Society 

 has been formed for the granting of premiums for the killing of 

 animals preying upon the eider, and, last year, 1155 such prizes 

 were awarded. 



There has been a very marked increase in the number of 

 visitors to the South Kensington Museum during the last year, 

 the numbers rising from 788,412 in 1887 to 897,225 in i888. 

 But this increase of 108,813 is quite put in the shade by that of 

 500,582 at the Bethnal Green Museum, which, in its total of 

 910,511 for the past year, has, as will be seen, distanced the 

 parent institution. This great influx of visitors, more than 

 double that of the previous year, was, no doubt, in great mea- 

 sure due to the exhibition there of Her Majesty's Jubilee presents 

 after they had ^been shown to the West End at St. James's 

 Palace. But some part of the increase must be attributed to 

 the fine collection lent by the Hon. W. F. B. Massey Main- 

 waring. The increase in numbers at South Kensington was not 

 confined to the main Museum, but extended to the separate 

 collections — the Science Museum and the India Museum — 

 which are in the galleries at the west side of Prince's Gate, and 

 which are not open in the evening, as are, on three evenings in 

 the week, the collections in the main building on the east of 

 Prince's Gate, and the Bethnal Green Museum. The numbers 

 visiting the Science collections increased from 177,465 in 1887 

 to 258,796 in 1888, notwithstanding the fact that the galleries 

 have been severed by the new road cut across the Horticultural 

 Gardens, while the visitors to the India Museum increased from 

 116,574 to 152,911. The numbers of visitors are taken in all 

 cases by turnstiles. 



We have received several letters on " Hares Swimming." 

 Mr. G. H. Kinahan writes that he believes the phenomenon to be 

 not uncommon. " When I was stopping at Inver Lodge, Co. 

 Galway," he says, " the keeper told me a hare had a nest with 

 three young ones on a small island in the lake, and that it left 

 them most of the day-time. I went with him to the island, which 

 was about 30 yards in diameter, and about 100 yards from the 

 shore, and after searching it most carefully, we could only find 

 the three leverets. Sheep are animals that in general keep out of 

 water, yet in Connemara I have seen them quite naturally swim- 

 ming a river or even a lake." " E. H." writes : — " I was by 

 the little River Arun below the old mill at Pulborough one 

 day, when I saw a hare quietly cantering down the opposite 

 field towards the river. A bank hid the actual crossing of the 

 river from me ; but when the hare emerged from the water into 

 the field in whieh I was standing, I was amused to see the dog- 

 like fashion in which it stood and shook off the moisture, 

 scattering the spray far and wide, before resuming its leisurely 



