40 



KNOWLEDGE. 



January, 1913 



is converted into the base by replacing the CI with 

 OH by treating with silver oxide in the usual 

 manner. The base, when distilled, breaks up into 

 isoprene, thus 

 (CH 3 ) .(CH S ), 



";n.ch 2 .ch(ch :) ).ch 2 .ch 2 .n^ >- 



H(T 



OH 



CH 2 = C(CH :i )— CH=CH 2 + 2N(CH») S + 2H 2 (). 



Isoprene. 



Homologues of isoprene ma\- be produced in a 

 similar manner. 



By this paracresol method Hofmann produced 

 gallons of isoprene, which was converted into rubber 

 by polymerising by heating, and the rubber thus 



obtained was made into a motor-car tyre. One 

 driving wheel of a motor-car was fitted with a tyre 

 made of the best natural Para rubber (the best 

 natural rubber known), and the other with this 

 synthetic rubber ; after six months' hard wear the 

 Para tyre was badly worn, while the synthetic tyre 

 was practically untouched — a conclusive proof of 

 what can be done with synthetic rubber. 



Quite recently (see The Daily Mail, September 

 11th, 1912,) in New York, two excellent specimens 

 of synthetic rubber tyres, one a heavy five-and-a-half- 

 inch and the other a four-inch tyre, were exhibited 

 before a gathering of the world's chemists, by 

 Fr. Baver & Co. 



(To be continued.) 



NOTICES. 



SECOND-HAND APPARATUS.— A very useful catalogue 

 of second-hand apparatus and accessories has been issued by 

 Messrs. H. F. Angus & Company, of 83, Wigmore Street, 

 London. It specially deals with microscope stands, objectives, 

 and eye-pieces by all the well-known makers. There are also 

 lists of accessories, and of other instruments, such as tele- 

 scopes, field-glasses, spectroscopes, and photographic lenses. 

 It is practically certain that if there were not facilities for the 

 obtaining of apparatus at a cheap rate many useful experi- 

 ments would remain unmade, and it is a great advantage to 

 workers that Messrs. Angus will give a written guarantee that 

 any second-hand instrument which they sell has been tested 

 and adjusted so that it will work as well as ever it did. 



MESSRS. W.WATSON & SONS, LTD.— We have pleasure 

 in announcing that Messrs. W. Watson & Sons have moved 

 their electro-medical department from their establishment in 

 High Holborn (which they have occupied for more than fifty 

 years) to their new premises at 184, Great Portland Street, W., 

 where, owing to the greater scope, this section of their business 

 can now be carried on more advantageously than hitherto. 

 For not only are there show-rooms for the display of electro- 

 medical apparatus in every branch, but a testing laboratory 

 has been provided where all the appliances will be carefully 

 examined and checked on their receipt from the works at 

 High Barnet before they are despatched to customers. 



LANTERN SLIDE GALLERY.— Mr. J. H. Steward has 

 opened at 406, Strand, a new lantern slide gallery, wherein 

 can be seen at any moment two thousand slides, illuminated 

 by electric light. Here will be found a good selection of 

 slides of scientific interest, in addition to full series of photo- 

 graphic views of excellent quality, both plain and coloured, 

 from all parts of the world. We noted specially a fine series 

 of astronomical slides, produced by the Woodburygravure 

 process. We welcome this addition to the very small number 

 of lantern slide galleries in London. 



NOTES ON NEW BOOKS.— From Messrs. Macmillan 

 and Company comes an illustrated list with descriptive 

 notes of their new and forthcoming books. The short 

 paragraphs have advantages in some ways over reviews, 

 because the publisher can say in them exactly what he wants 

 his prospective readers to know about the book. 



THE ROYAL INSTITUTION.— The following are the 

 Lecture arrangements at the Royal Institution before Easter : — 

 Professor Sir James Dewar, a Christmas Course of Six 

 Experimentally Illustrated Lectures, adapted to a Juvenile 

 Auditory: 1, Alchemy; 2, Atoms; 3, Light; 4, Clouds; 



5, Meteorites ; 6, Frozen Worlds. Professor William Bateson, 

 Six Lectures on "The Heredity of Sex and some Cognate 

 Problems." Professor H. H. Turner, Three Lectures on the 

 Movements of the Stars: 1, "The Nebular Hypothesis"; 



2, " The Stars and their Movements " ; 3, " Our Greater 

 System." Mr. Seton Gordon, Two Lectures on " Birds of the 

 Hill Country." Professor B. Hopkinson, Two Lectures on 

 " Recent Research on the Gas Engine." Sir Sidney Lee, 

 Three Lectures on " The Dawn of Empire in Shakespeare's 

 Era." Mr. W. B. Hardy, Two Lectures on " Surface Energy." 

 Dr. H. Walford Davies, Three Lectures on Aspects of 

 Harmony: 1, " Chord Progression " ; 2, " Added Dissonance " ; 



3, "The New Whole Tone Chord and its Predecessors." 

 Professor Sir J.J. Thomson, Six Lectures on " The Properties 

 and Constitution of the Atom." The Friday Evening Meetings 

 will commence on January 17th, when Professor Sir J. J. 

 Thomson will deliver a Discourse on " Further Applications 

 of the Method of Positive Rays." Succeeding Discourses 

 will be given by Professor J. O. Arnold, Mr. George M. 

 Trevelyan, Sir John Murray, Professor Andrew Gray, Mr. 

 Spencer V. Pickering, Mr. C. T. R. Wilson, Professor the 

 Hon. R. J. Strutt, and Mr. A. E. H. Tutton. 



CLASSES IN PHOTOGRAPHY.— Mr. Edgar Senior's 

 work at the following various educational centres begins on 

 the dates set forth below. 



Battersea Polytechnic. — Tuesday, January 14th. 



South Western Polytechnic, Manresa Road, Chelsea.- — 



Monday, January 13th. 

 The London Central Y.M.C.A., Tottenham Court Road. — 

 Friday, January 10th. 



LANTERN SLIDES.— The new catalogue of lantern 

 slides issued by Messrs. Flatters & Garnett, Ltd., of Dover 

 Street, Manchester, consists of one hundred and thirty-six 

 pages, and many of the subjects in the list are from negatives 

 illustrating natural history and cannot be obtained elsewhere ; 

 such, for instance, as the series of British birds, nests and eggs 

 by Mr. Stanley Crook, and the British Plant Associations 

 photographed by Mr. W. B. Crump. We can give the highest 

 praise to the specimen slides which Messrs. Flatters and 

 Garnett have submitted to us for review. The bird-photo- 

 graphs are excellent, as are the plant studies, and all of them 

 should prove extremely useful to lecturers who have not the 

 opportunity of making their own slides, or who wish to fill up 

 gaps in their series. Teachers, who as a rule are not blessed 

 with large means, should be able to take advantage of the 

 slides, as they are by no means expensive. The examples 

 sent to us are contained in one of Messrs Flatters & Garnett's 

 special mahogany dispatch boxes, which we commend to our 

 readers, and which are described on the cover of the catalogue. 



