154 



SCIENCE 



[N. S. Vol. LIV. No. 1390 



Of these main divisions there are 14, covering 

 the entire range from normal acid to normal 

 alkaline reaction. The 125 mm. disk is 

 mounted by means of a central pivot on a 

 second disk, having its scale of voltage around 

 the circumference of the first. The range of 

 the latter extends from 0.24 to 1.17 volts. 

 Concentric with the disks is a movable arm 

 of transparent celluloid, with a radial hair- 

 line scribed ujxin it, to facilitate making 

 readings. The points on the voltage scale cor- 

 responding to the potentials of tenth-normal, 

 normal and saturated KCl calomel cells are 

 marked, as a matter of convenience. The 

 temperature for which the slide-rule gives 

 correct readings is 25° C. 



To use the instrument, the zero mark of 

 the circular scale is set on the voltage corre- 

 sponding to the reference electrode being used. 

 The hair-line is set to indicate the measured 

 voltage, and the corresponding ph and Ch* 

 readings appear under the hair-line on the 

 inner disk. Settings are possible to an ac- 

 curacy of ±0.5 millivolt. 



The slide-rule can be used equally well 

 when the reference electrode, instead of being 

 the usual calomel half-cell, is a hydrogen elec- 

 trode of knoivn potential relative to the stand- 

 ard solution in which it is immersed. What- 

 ever the nature of the iixed electrode, the 

 change in potential difference at the ter- 

 minals of the gas chain is 59.1 millivolts for 

 each decimal change in the concentration. 

 The graduation of the inner disk , is based 

 upon this assumption, which makes it appli- 

 cable to any case. 



Because of the fact that so few data are 

 available on the variations of gas chain elec- 

 tromotive forces with temperature, it seems 

 advisable, pending an accumulation of reliable 

 information on this point, to make measure- 

 ments at a temperature of 25° whenever this 

 is possible. 



Paul E. Klopsteq 



mathematics in spanish-speaking 

 countries 

 The Spanish-speaking countries publish 

 only one journal devoted to advanced mathe- 



matics, which is now called Bevista Mate- 

 matica Hispano-Americana and is published 

 at Madrid, Spain, under editorship of J. Eey 

 Pastor. In view of the fact that the professors 

 of mathematics in so many countries can ob- 

 tain no other advanced mathematical journal 

 in their own language one might suppose that 

 this periodical would not suffer for want of 

 suitable manuscripts or sufficient financial 

 support. 



Such a supposition is, however, not in ac- 

 cord with the facts, judging from a call is- 

 sued recently by its editor. In this call it is 

 stated that there is now an. almost complete 

 lack of Spanish mathematical production and 

 that it has been necessary therefore to publish 

 an excessive number of articles by the same 

 authors. It is also stated that nearly all 

 Spanish professional mathematicians occupy 

 the position of spectators and critics, and thus 

 place the burden of doing the work connected 

 with the periodical on the shoulders of one or 

 two men. 



In view of the fact that in the English- 

 speaking countries of America the mathe- 

 matical journals are now overcrowded by 

 suitable manuscripts offered for publication it 

 is interesting to note that just the opposite is 

 true in the Spanish-speaking countries of this 

 continent. As was noted in Science, N". S., 

 volume 34, page 372, the Spanish-speaking 

 people organized a mathematical society in 

 1911. This society has been fairly successful 

 in awakening among them an interest in the 

 newer fields of mathematics, but, judging from 

 the call noted above, which was directed to 

 the members of this society, it seems that this 

 interest is still far from being general and 

 effective. 



G. A. MiLLEE 



Univeesitt of Illixois 



the earliest bees, wasps and ants 



It seems desirable to correct some state- 

 ments appearing in text4)ooks of geology, 

 which lead students to imagine that we are 

 acquainted with bees, wasps and ants from 

 Mesozoic strata. Thus, Professor J. W. Miller, 



