• 7 6 



SCIENCE-GOSSIP. 



Fig. 



Heat for Advanced Students. By Edwin Edser, 

 A. K.C.S. viii + 470 pp. , 7 in. x 4! in., illustrated by 

 213 figures. (London : Macmillan & Co. 1899.) 

 4s. 6d. 



This book will certainly prove a welcome one 

 among students of Heat. There are a good many 

 text-books on Heat already published, but they do 

 not show the superior treatment that marks Mr. 

 Edser's book throughout its 466 pages. The whole 

 matter is compiled in an excellent manner, and the 

 subject is brought quite up to modern knowledge by 

 the insertion of some recent researches. Each 

 division of the subject is treated with remarkable 

 clearness, so that an attentive reader, if he has 

 already studied Heat a little, will not have much 

 difficulty in mastering the contents of the present 

 volume. Numer- 

 ous experiments 

 are described in 

 detail, and many 

 new pieces of 

 apparatus figure 

 among the 214 

 illustrations. Of 

 these, special 

 mention may be 

 made of the 

 following. Fig. 

 22 illustrates 

 Weedon's pa- 

 tented apparatus 

 for the absolute 

 coefficient of expansion of solids, which has already 

 been described in detail and illustrated in Science- 

 Gossip {vide p. 197, December 1898). One of its 

 advantages is the direct measurement of the expan- 

 sion by means of micrometer gauges. An elegant 

 but simple apparatus is that illustrated in fig. III. 

 This is Dr. Lehfeldt's 

 arrangement for the 

 comparison of vapour 

 pressures of liquids. 

 The tubes and bulbs 

 are first emptied and 

 dried, the capillary 

 ends D D' are sealed 

 off, and the whole 

 arrangement exhausted 

 by connecting B' with 

 a mercury pump, after 

 which B' is sealed off, 

 disconnected from the 

 pump, and placed be- 

 neath mercury in a 

 vessel, when it has its 

 end broken off. The 

 mercury rises in the 

 tubes A to a desired 

 height, then B' is finally 

 sealed off. In a similar 

 manner the bulbs C C 

 can be partially filled 

 with the liquids of 

 which the vapour pres- 

 sures are to be com- 

 pared. The whole arrangement can then be 

 placed in a bath and heated to any desired 

 temperature. The difference in level of the 

 mercury surfaces in the gauge A gives the 

 difference between the vapour pressures of the 

 two liquids. 



Weedon's Patent Expansion Apparatus 

 (Heat for Advanced Students.) 



Fit;, in. Lehkeldt's 

 Vapour Pressure. 



(Heat for Advanced Students.) 



An ingenious apparatus, designed by the author 

 for comparing the relative conductivities of vari- 

 ous metals, is described and illustrated on pp. 

 426-427. It consists essentially of a metal pot, 

 through the bottom of which are soldered the ends 

 of the various rods, which extend downwards. Each 

 rod is provided with a small light metal index, as 

 shown in fig. 199, and which slides easily upon its 

 rod. Before an experiment is made these indexes 

 are pushed up until the top wire ring of each is in 

 contact with the bottom of the vessel. They are 

 then held there with wax. Hot water or oil is now 

 poured into the vessel, and, as the heat is conducted 

 along the rods, the wax becomes melted, and the 

 indexes gradually slide down through different dis- 

 tances, depending upon the conductivities of the rods. 

 The squares of the distances are proportional to the 



conductivities. 

 U n fo r t u n ate- 

 ly, some errors 

 have crept into 

 this excellent 

 book, which, 

 no doubt, will 

 be corrected in 

 the next edition. 

 These are the 

 following: — P. 6, 

 in the calculation 

 at bottom of 

 page, r should 

 = 1-5, not -15; 

 p. 14, line 15, for 

 Reaumur temp : x 9 , Reaumur temp : x 9 



4 " I - +32! 



p. 14, line 16, for (Fah " temp. -32)+ 5 read 



(Fah=temp:-32)x 5 . p _ ^ Km ^ fg) , t0Q = {1 + 



at 3 ) -I read t°C = (I + at) 3 - I ; p. 205, line 22, for 

 m read E ; p. 300, second line from bottom, for ' 

 (pv + dv) read p(v + dv). The book is one of the 

 brightest and most useful physics text-books we have 

 met with for a considerable time.—/. Q. 



Experimental Physics. By the late Eugene 

 Lommel. xxi + 664pp., 9 in. x6in., with numerous 

 illustrations. (London: Kegan Paul & Co. 1899.) 

 15s. 



The translator of this book has well succeeded in 

 the arduous task of presenting to the English-speak- 

 ing student one of 

 the German stand- 

 ard text - books, 

 and also in keep- 

 ing strictly to the 

 method of the 

 author — the late 

 Professor von 

 Lommel. The 

 whole subject of 

 Physics is treated 

 in a general ex- 

 perimental manner 

 and with little ma- 

 thematics. The 

 book has been 

 divided into ten 



parts, viz.: Motion, Solids, Liquids, Gases, Heat, 

 Magnetism, Electricity, Electrical Currents, Waves 

 and Sound, Light. Each of these divisions is 



Fig. iq8. Edser's Conductivity 



Apparatus. 



(Heat for Advanced Students.) 





