July 14, 19 10] 



NATURE 



51 



wliich is only 0-07 inch more than the average, but rain 

 (ell on sixteen days. The mean temperature was about 

 1° above the normal, and the duration of bright sunshine 

 was twelve hours less than usual. 



Messrs. R. \V. Paul have issued a pamphlet entitled 

 " The Equipment of a Modern Elementary Electrical 

 Laboratory," in which a standardisation of instruments is 

 advocated with the view of attaining an interchangeabi'ity 

 of instruments, shunts, and multipliers so that any one 

 instrument may be easily adapted for measuring a wide 

 range of currents and voltages. The instrument recom- 

 mended for the use of elementary students is the unipivot 

 galvanometer, which has a range of 240 microamperes 

 unshunted, and may therefore be used instead of a mirror 

 galvanometer for many experiments. An appendix gives 

 a list of experiments suggested for an elementary course 

 in electrical engineering and the apparatus required for 

 cairving them out. We think that Messrs. Paul advocate 

 too strongly the advisability of making the carrying out 

 of experiments easy to the student. A great part of the 

 benefit to be derived from an experimental course lies in 

 learning to overcome practical difficulties, and students 

 brought up on experiments that are so carefully prepared 

 as to eliminate such difficulties do not, as a rule, become 

 skilful experimenters in the more advanced stages. 



Vol. vii. of Contributions from the Jefferson Physical 

 Laboratory of Harvard University contains 463 pages of 

 reprints of fifteen papers which have appeared in the 

 American scientific periodicals during the past year. Of 

 these papers, we have already noticed one in these columns, 

 th'at on certain thermal properties of steam, by Mr. H. N. 

 Davis. Another of exceptional interest, by Mr. H. W. 

 Morse, deals with the evaporation from a solid sphere. 

 The spheres experimented on were of iodine, and had radii 

 between 0-2 and i millimetre. They were supported on a 

 thin lamina of glass attached to the end of a thin fibre of 

 glass, the other end of which was clamped firmly in a 

 horizontal position, i.e. the micro-balance of Salvioni. The 

 evaporation took place in a large box with glass sides, 

 through which the deflection of the micro-balance was 

 measured by means of a microscope. The rate of evapora- 

 tion proved to be proportional to the radius of the drop, 

 and not to its surface. 



An advance copy has reached us of the catalogue of 

 mathematical and scientific instruments to be on view 

 at the International Exhibition at Brussels this year. This 

 catalogue has been prepared under the auspices of the 

 Board of Trade by the National Physical Laboratory ; it 

 refers only to the exhibits of British manufacturers. It 

 includes detailed descriptions and illustrations of many of 

 the instruments. A glance through this catalogue gives a 

 very good idea of the rapid advances that are being made 

 in the design of physical apparatus. It is invidious to 

 select any names of exhibitors ; it is enough to say that 

 most of the leading makers of electrical, optical, survey- 

 ing, navigational, and meteorological instruments are 

 amongst them, and that the addition of historical refer- 

 ences and lists of original publications makes the book a 

 valuable one for reference. The price is only sixpence post 

 free on application to the director. Exhibitions Branch, 

 Board of Trade, Broadway, Westminster. We may add 

 that the catalogue has been compiled free of cost to the 

 exhibitors, and it is Tioped that the prospect of the publica- 

 tion of a similar catalogue for the International Exhibition 

 It Turin next year wfll induce other firms to avail them- 

 - Ives of the many facilities which the new Board of Trade 

 <l ;iirlni<>nt now affords to exhibitors. 

 NO. 2124, VOL. 84] 



We have received from Messrs. Baird and Tatlock 

 (London), Ltd., a copy of the gas-calculator designed by 

 Dr. R. C. Farmer. The diagram consist's of four vertical 

 lines ; the two on the left are graduated in temperatures 

 for wet and dry gas respectively ; the line on the right is 

 graduated in pressures (mm.). A celluloid strip bearing 

 a black ruled line is laid across the observed pressure and 

 temperature of the gas, and the corrected volume of i c.c. 

 of gas is read off directly on the middle line. The latter 

 is also graduated to read the logarithm of the weight of 

 I c.c. of nitrogen. It is claimed to give the volume with 

 an accuracy of i part in 5000, and this we have found to 

 be the case if 0-00367 be taken as the coefficient of ex- 

 pansion of the gas in question. The diagram is extremely 

 rapid and convenient in use, but it should not be lost 

 sight of that an accuracy of i in 5000 is not possible with 

 the more expansible gases. 



The synthesis of camphoric acid, as announced by 

 Komppa in 1903, is adversely criticised by M. Blanc (of 

 the Sorbonne, Paris) and Dr. J. F. Thorpe in a recent 

 communication to the Journal of the Chemical Society. 

 One of the critical stages in the synthesis consists in the 

 methylation of a diketoapocamphoric acid with the view of 

 completing the total of ten carbon atoms present in the 

 molecules of camphor and of camphoric acid. Using the 

 ester of the acid, the methylation-product is a crystalline 

 substance melting at 85° to 88°, and was supposed by 

 Komppa to have the new methyl-group attached to carbon ; 

 it is now shown that the methyl-group is easily removed 

 by cold caustic potash, and is undoubtedly attached to 

 oxygen and not to carbon ; the reduction of the compound 

 to camphoric acid would therefore involve an important 

 molecular re-arrangement, and even if it were effected 

 could scarcely be regarded as a direct building up of the 

 camphor molecule. 



We have received from the Thermal Syndicate, Ltd. 

 (Wallsend-on-Tyne), its list of pure fused silica ware. 

 The manufacture of articles from fused silica has engaged 

 the attention of experimenters for a long time ; but, owing 

 to the high fusing point of quartz, the difficulties met with 

 in manufacturing articles were very considerable. The 

 Thermal Syndicate has developed a most successful 

 process for fusing and working silica in an electric furnace. 

 Only in 1904, a basin of 25 cubic centimetres capacity was 

 considered an achievement ; but at the present time, pipes 

 12 inches in diameter and 30 inches long, and vessels of 

 50 litres capacity, are being manufactured. The articles 

 manufactured by the Thermal Syndicate which are placed 

 on the market under the trade name " Vitreosil " are of 

 very varied character. The ware is used in the manufacture 

 of sulphuric acid, for nitre pot pipes, and for the basins 

 for cascade concentrators, of which there are more 

 than 600 in use in the British Isles, representing an 

 output of about 22,000 tons of acid. It is also used to a 

 smaller extent in the manufacture of nitric acid, and for 

 making the pipes which carry the gases from the roasters 

 in the manufacture of hydrochloric acid. It can be used 

 for making condenser worms, small electrolytic tanks 

 where the process requires the maintenance of a high 

 temperature, and so on. The great advantage of 

 " Vitreosil " is that it is practically unaffected by tempera- 

 ture changes, the coefficient of expansion being about one- 

 seventeenth that of glass. Owing to this property, its high 

 fusibility and its resistance to acids, quartz is now being 

 very largely used for the manufacture of laboratory 

 apparatus. 



