72 



KNOWLEDGE 



[April 1, 1893. 



The idea that water on freezing gets rid of its impurities 

 turns out to be another instance of a popular fallacy. 

 Eecent careful experiments show that the average amount 

 of impurity retained by ice is 34-3 per cent, of organic 

 matter and 21 -2 per cent, of inorganic matter. In view 

 of these results it behoves those who supply ice to shops 

 to exercise some care as to the source from which it comes. 



A translation of Prof. Weisman's "Das Keimplasma " 

 (the Germ Plasm) has been issued in " The Contem- 

 porary Science Series" (Walter Scott). The translators 

 are Prof. W. N. Parker and Harriet Ronnfeldt, who have 

 done their work carefully. Prof. Parker has had the great 

 advantage of being able to consult Prof. Weisman per- 

 sonally with regard to many of the more difficult passages. 

 — »-♦-• — 



An important paper on " Fossil Mammals of the 

 Wahsatch and Wind Eiver Beds," by H. F. Osboru and 

 .J. L. Wortman, has been issued as a bulletin by the 

 American Museum of Natural History, and has also been 

 ■ published separately. It is principally devoted to a 

 description of a collection made by Dr. Wortman during 

 the summer of 1891. The authors claim that many new 

 facts of great interest are brought out by the material in 

 the collection. , . , 



M. Moissan, the eminent French chemist, who succeeded 

 a few weeks ago in producing diamonds artificially, con- 

 tributes to the Vomptes Eendus of March 6th some further 

 observations on the chemical properties of the diamond. 

 He finds that the temperature of combustion of diamonds 

 in oxygen varies with dift'erent specimens from 760° C. to 

 875^ C. In general, the harder the diamond the higher is 

 its temperature of combustion. Dry chlorine and hydro- 

 fluoric acid vapour are incapable of acting upon the 

 diamond until a temperature of about 1200- C. is reached. 

 At this temperature, however, fused carbonates of potassium 

 and sodmm easily dissolve it, carbonic oxide being evolved 

 by the reaction. , .. 



Dr. Bashford Dean, who was sent by the United States 

 Fish Commission in 1891 to study the cultivation of the 

 oyster in Europe and America, has just issued two reports 

 {Bulletin U.S. Fish Comm., Is90), one dealing with 

 " Oyster Culture in France," the other with the " Natural 

 Oyster Grounds of South Carolina." The first report 

 shows the very high state of perfection to which the culti- 

 vation of the oyster has been breught in France. The 

 second report deals in the fullest manner with the natural 

 conditions affecting the growth, the nature of the bottom, 

 the food, enemies, &c., of the South Carolina oyster, and 

 is illustrated by reproductions of photographs. 



The Geolofiical Mar/azine for February contains an in- 

 structive sketch of the life and work of the late Sir Richard 

 Owen from the facile pen of the editor. Dr. Henry Wood- 

 ward, who was his official colleague during a quarter of a 

 century. We will only quote the following paragraph : — 

 " The success that attended him in his long life resulted 

 from a combination of circumstances. Everybody will 

 readily admit the fact of Professor Owen's extraordinary 

 genius, his sagacity in interpretation, and his remarkable 

 ability as a lecturer ; but behind these he owed very much 

 to his indomitable energy and power of sustained work, to 

 his marvellous How of language, to his vigorous bodily 

 health, and, in controversy, not a little to his cleverness 

 both in defence and attack. His courteous manners, when 

 dealing with the general public, were proverbial, and also 

 the marked attention which he paid to the rank of the 

 individual." 



The Rev. F. -T. Smith, 'Millard Lecturer at Trinity 

 College, Oxford, points out in Nature of March 9th that 

 an efficient screen from the magnetic influence of a large 

 dynamo is obtained by building two brick walls a short 

 distance apart and filling the interspace with scrap iron. 

 A screen of this character has been constructed to protect 

 the physical instruments of the Millard Laboratory from 

 the intense magnetic field of the transformer of the Oxford 

 Electric Lighting Company, and it answers the purpose 

 extremely well. , , , 



The Commission appointed to investigate the subject of 

 electrical communication with lighthouses and Ughtships 

 has recently finally considered an ad interim report. This 

 report deals with that portion of the evidence relating to 

 the necessity of establisliing telegraphic communication 

 with lightships and lighthouses on the British coast. It 

 is understood that the Commissioners recommend expe- 

 riments being made in the matter of direct communication 

 between lightships, &c., and the shore upon some of the 

 most dangerous shoals and sands. 



For some time M. Masoart has used, under the name of 

 a fjravity-harometer, an instrument by means of which the 

 variation of gravity between different places can be 

 determined. The instrument has recently been employed 

 in determining whether there are temporary variations of 

 gravity in one and the same place, and M. Mascart finds 

 anomalous disturbance, which he is unable to attribute to 

 changes of temperature or other physical changes affecting 

 the instrument. He is inclined to treat them as evidence 

 of variation in the force of gravity, and it is pointed out 

 that observations of this kind will no doubt present a 

 peculiar interest in volcanic districts if the changes are due 

 to displacement of masses in the interior. (Philosophical 

 Magazine, March, 1893.) 



Two important papers upon the ready preparation of 

 large quantities of the more refractory metals, by means of 

 the electric furnace, are contributed by M. Moissan to the 

 Cowptex Fiendus. The electric furnace is simply a small 

 fui-nace constructed of lime, so arranged that it can be 

 intensely heated by a very powerful electric arc. A 

 quantity of magnesia, which M. Moissan finds to be per- 

 fectly stable, even at this high temperature, is first placed 

 in the cavity of the furnace, and upon this the crucible of 

 retort-carbon, containing a mixture of powdered carbon 

 and the metallic oxide to be reduced. In this way 

 M. IMoissan has succeeded in rapidly preparing considerable 

 quantities of the metals of the alkaline earths, calcium, 

 strontium, and barium. , , , 



There is little doubt that exaggerated statements are 

 frequently made with regard to the speed of flight of birds. 

 A writer in Science records a case in which a couple of 

 wild ducks started off' at full speed in front of a train 

 which had disturbed them ; and, though the train was 

 running at the rate of only thirty-seven miles per hour, the 

 birds were overtaken. In a letter to Nature on the same 

 subject, Mr. H. Withington gives an instance of a pair of 

 turtle-doves flying at a speed rather less than a train 

 travelling about forty miles per hour. But the turtle-dove 

 is probably below the average pigeon in point of flying 

 capacity. As Mr. Withington remarks, " it certainly 

 cannot be compared with the passenger pigeon of America, 

 which has frequently been killed in the neighbourhood of 

 New York with Carolma rice still undigested in its crop, 

 having probably accomplished a journey of between 300 or 

 400 miles in about six hours, giving the high record of 

 sixty miles an hour for sis hours in succession." 



