324 Scientific Intelligence. 



present, a black coloration is immediately produced, due to the 

 formation of nitrogen iodide. In doubtful cases, where iodine 

 may be set free, a slight excess of the hypochlorite is added in 

 order to dissolve the iodine. The color is sufficiently stable to 

 allow of calorimetric comparison with known amounts of ammo- 

 nium chloride solution. The authors claim that foreign substances 

 interfere with this reaction less than with Nessler's test, and that 

 other nitrogenous substances do not yield the same reaction.— 

 Comptes Hendus, cxl, 374. h. l. w. 



4. Radio-tellurium. — Maeckwald has worked up the crude 

 tellurium obtained from about 15 tons of pitchblende. By dis- 

 solving the material and precipitating with sulphur dioxide, about 

 16 g. of a mixture of selenium, tellurium and radio-tellurium were 

 obtained. Upon oxidizing this with nitric acid, evaporating to 

 dryness and warming with solution of ammonia, a residue weigh- 

 ing about 3 mg. was obtained, which apparently contained prac- 

 tically all of the radio-active material, and possessed "enormous" 

 activity. It is Marckwald's opinion that his radio-tellurium is a 

 distinct substance, not identical with polonium. — Berichte, xxxviii, 

 391. h. l. w. 



5. Conversations on Chemistry, Part I, General Chemistry / 

 by W. Ostwald. Authorized Translation, by Elizabeth Cath- 

 erine Ramsay. 12mo, pp. 250. New York, 1905, John Wiley & 

 Sons. — The eminent author was led to write this work, for one 

 reason, on account of the benefit that he derived from using a 

 book of similar character, Stockhardt's " Schule der Chemie," as 

 his first text-book of chemistry. As another reason, he hopes to 

 overcome the tendency to onesidedness due to the great attention 

 paid to organic chemistry at the present time in Germany, by 

 presenting a treatise on general and physical chemistry, since 

 these may be regarded as the foundation for all real chemical 

 education. 



The form of dialogue between master and pupil has been 

 adopted, because it appeared to occupy no more space than ordi- 

 nary description, while the impression made is much more " pene- 

 trating and lively." This is going back to a form of text-book 

 considerably used by our grandparents, but, while we may fre- 

 quently smile at the almost superhuman aptitude of the pupil in 

 asking the proper questions and in making appropriate comments, 

 the impression gained by an examination of this little book is 

 that it is a most excellent and valuable one. 



The book under consideration, which is the first part of a series, 

 deals only with common and simple chemical and physical phe- 

 nomena. No attempt is made here to introduce any chemical 

 theories, but many points of physics are very clearly explained. 

 The experiments presented are very satisfactory ones. The trans- 

 lator has done good work, and few traces of the German idiom 

 are evident ; indeed, there is sometimes doubt in regard to the 

 original language used to express youthful astonishment, as, for 

 example, where the pupil exclaims, " Oh, how ripping," upon 

 observing a striking experiment. h. l. w. 



