156 



NATURE 



[December 14, 1899 



«ngraved from a photograph taken in 1846. The volume will 

 doubtless be treasured by Lord Kelvin's many admirers, as a 

 slight tribute of regard for the versatility of his genius. 



The British Medical Journal announces that Dr. Yersin, 

 -whose name is well known for his researches on the plague, 

 has been charged by the Government of Cochin China with a 

 special mission to Java. 



IT is reported in Science that the Russian Astronomical 

 Society has finally given up its attempt to revise the Julian 

 •calendar. The reason assigned for its failure by the Society is 

 •' the impossibility of establishing an agreement between the 

 ■dates of the religious festivals appearing in both calendars." 



In connection with the Institution of Electrical Engineers, a 

 number of local centres are being established where papers will 

 t)e read and discussed at the same time, or shortly after, their 

 reading in London. In Cape Town these informal meetings 

 have been held for some time past, and advance copies of the 

 Institution's papers have been read at them. A meeting for the 

 formation of a north-eastern centre was to be held yesterday at 

 -the Durham College of Science, and the Council have received 

 a petition for the establishment of a similar organisation in 

 Dublin. 



We regret to see the announcement of the death of Mr. N. 

 E. Green, F.R.A.S. An artist by profession, Mr. Green was 

 well known for his admirable astronomical drawings — especially 

 those of Jupiter and Mars. On the occasion of the opposition 

 •of the latter planet in 1877 he went to Madeira, where he made 

 a fine series of drawings, a selection from which was published 

 in vol. xliv. of the Memoirs of the Royal Astronomical Society. 

 A number of his drawing? of Jupiter were reproduced in vol. 

 -xlix. of the same publication, and he left behind him a long 

 series of unpublished lunar and planetary drawings. Mr. 

 Green was President of the British Astronomical Association in 

 1897-98. 



The Institution of Electrical Engineers held their annual 

 •dinner on Wednesday, December 6, in the Hotel Cecil, Prof. 

 Silvanus Thompson in the chair. Among the speakers was 

 Lord Kelvin who proposed the toast of " Science." In the 

 ■course of his remarks, he said : — When the electric telegraph 

 K;ame into practical existence in 1837, when ten years or so later 

 the first submarine cables connected England and the Continent 

 •of Europe, and when another ten years or .so saw the first 

 Atlantic cable laid, electrical science in all the Universities of 

 Europe was in a very backward state compared with the position 

 in which it is now. A very great stimulus indeed was given 

 ito its study from its application to electric telegraphs, and 

 especially to the great system of electric measurements which is 

 •so valuable now in pure science— a system which originated 

 ■certainly not among practical engineers, but among University 

 professors. Gauss and Weber gave from Germany the founda- 

 tion of the .system of electric measurements, the benefits of 

 ■which are now enjoyed, and the first practical use of which was 

 Tnade in connection with submarine cables. 



A PAPER on the manufacture of artificial silk or lustro- 

 .cellulose was read by Mr. Joseph Cash at a meeting of the 

 Society of Arts on December 6, and is printed in the fournal of 

 the Society. A public company for the manufacture of this 

 material by the Chardonnet process has been formed in England, 

 and the factory will be capable when filled with machinery of 

 producing 7000 lbs. of artificial silk per week. The first stage 

 of manufacture is the nitration of cotton or wood pulp producing 

 pyroxyline, discovered by Pelouze in 1838. The greatest care 

 must be employed in conducting this operation, as it is the most 

 important one in the whole process ; mistakes sometimes even 

 NO. 1572, VOL. 61] 



occur at the long-established factory at Besan9on, in France. 

 The process of nitration of cellulose is the displacement of a 

 few molecules of hydrogen by nitric peroxide. There are 

 several varieties of pyroxyline which are obtained by using 

 different mixtures of acid. When the pyroxyline has been ob- 

 tained, it is placed in a cylinder with a mixture of alcohol and 

 ether; the cylinder is then slowly revolved for twelve hours, 

 with the result that the pyroxyline is dissolved and collodion is 

 produced. After filtration by forcing it through a sheet of 

 cotton-wool between calico, under a pressure of fifteen atmo- 

 spheres, the collodion is ready for use. 



For the manufacture of artificial silk a pressure of forty to 

 forty- five atmospheres is required to force the collodion from 

 the reservoirs to the spinning machines, which are constructed 

 with pipes running on each side. Into these pipes are screwed 

 a number of taps with a glass capillary tube fixed on the end, 

 called a silk-worm, through which the collodion is forced ; im- 

 mediately it comes into contact with the air it solidifies, enabling 

 the operative to take hold of the thread or silk, as it can now 

 be called, and convey it to the bobbin. From twelve to twenty- 

 four of these threads are run together on to one bobbin, accord- 

 ing to the size, of silk required, as is the case with natural silk. 

 After the silk has been dried it is very inflammable and quite 

 unfit for use in textile goods ; therefore, a process called deni- 

 tration is next carried out, which reconverts the product into 

 cellulose. One of the uses of the material is for mantles for the 

 incandescent gas light, it being found that the salts of the rare 

 metals can be mixed with the collodion with greater economy 

 than with any other thread. Large works are in operatijn at 

 Besan9on, in France, producing 7000 lbs. weight per week ; but 

 the demand is so great that extensions of the works are being made 

 in order to enable them next January to produce 2000 lbs. per 

 day. The production at Sprietenbach is 600 lbs. daily. Other 

 factories are about to be established in Belgium and Germany, 



Mention is made in Science Abstracts of a method of thaw- 

 ing water service pipes by means of electricity, successfully 

 used in Canada. The frozen pipes are thawed by passing 

 alternating currents through them. A pressure of twenty to 

 fifty volts is used, obtained from a portable transformer con- 

 nected with the street mains. A current of 200 to 300 amperes 

 is passed through the frozen pipe until the water flows freely, 

 which usually takes place in a few minutes. 



In 1894, Prof, van der Waals found a remarkable property 

 of the molecular potential function occurring in his theory of 

 capillarity, namely, that if a constant coefficient be left out of 

 account the potential of a homogeneous sphere at an external 

 point is the same function of the distance from the centre of 

 the sphere as if the whole mass were concentrated at the centre. 

 Dr. G. Bakker, writing in the Proceedings of the Roya 

 Academy of Sciences of Amsterdam, now investigates the most 

 general form of potential function possessing this property, and 

 he obtains for the potential at distance r the form 

 A.? - *'• + Be"- 



\r) 



1 + c. 



For the potential function required in the theory of capillarity 

 Dr. Bakker remarks that B = o. The author further investigates 

 whether it is possible to obtain a potential differing in form 

 from the Newtonian potential and satisfying the further con- 

 dition that the potential is constant throughout the interior of 

 a spherical .shell. It is found that a solution exists, but as the 

 expression for the potential function involves the radius of the 

 shell, the result is in no way contradictory to Laplace's con- 

 clusion that the Newtonian potential is the only potential 

 which is constant throughout the interior of a spherical shell, 

 irrespective of the size of its radius. 



