Chemistry and Physics. 81 



to the subject by describing the general processes and giving an 

 extensive series of simple gravimetric determinations (here called 

 estimations according to the British custom) suitable for the 

 practice of beginners. The more important methods of volu- 

 metric analysis are then taken up. The general quantitative 

 analysis covers a wide range of subjects, largely technical in 

 character; the analysis of ores, metals, alloys, fuels, fertilizers 

 and other products. It takes up also fire assaying, sanitary 

 water analysis, the analysis of milk, butter, alcoholic beverages, 

 sugar, tea, tanning materials, soap, oils, fats and waxes, and 

 technical gas analysis. One section of the book is devoted to 

 ultimate organic analysis and molecular weight determinations. 

 Although some of the topics are necessarily treated rather 

 briefly and incompletely, the book is an excellent one for giving 

 the student practice in nearly all of the usual work of the analy- 

 tical chemist. The methods are generally well selected and 

 clearly described, but there are naturally some variations be- 

 tween the British practice here given and what may be called the 

 best American practice in analysis. The book has found extensive 

 use as a text-book, and the new edition will doubtless be still 

 more popular. h. l. w. 



6. Positive Electricity — Sir J. J. Thomson asks: — (1) 

 Does a definite unit of positive electricity exist? (2) If so, 

 what is the size of the unit ? This paper introduces a discussion 

 upon these questions at the Winnipeg meeting of the British 

 Association and therefore contains matter previously printed. 

 There are, however, some new experiments upon the effect of 

 magnetic fields on positive and negative rays, which led the 

 author to elaborate theories in regard to neutral doublets. He 

 concludes that even at the start from the cathode the "canal 

 strahlen" include a large number of neutral doublets, if indeed 

 they do not wholly consist of them. Much space is given to 

 discussion of the neutral doublets, both in canal strahlen and 

 retrograde rays, which proceed from the cathode toward the 

 anode. It is supposed that these doublets are of the same 

 character from whatever kind of gas they originate. Thomson 

 refers to a former paper in w 7 hich he showed that if a vessel was 

 exhausted until the pressure was so low that the discharge 

 would not pass, and small quantities of hydrogen, helium, air, 

 oxygen, carbonic acid or argon were introduced so as to 

 raise the pressure sufficiently to produce a discharge, the velocities 

 of the particles were the same for all the gases. The paper 

 closes with description of a method of measuring the effective 

 magnetic field in the magnetic deflection of canal strahlen. — Phil. 

 Mag., Dec. 1909, pp. 821-845. j. t. 



7. Doppler Effect in Positive Mays in Hydrogen. — T. Royds 

 has studied this effect, both in front and behind the cathode. He 

 believes that the canal rays mostly start from the negative glow, and 

 believes that the commencement of the cathode glow corresponds 

 to the minimum Doppler effect when the cathode is viewed from 



Am. Jour. Sci.— Fourth Series, Vol. XXIX, No. 169.— January, 1910. 

 6 



