816 



SCIENCE. 



[N. S. Vol. III. No. 74. 



This octavo-volume contains six hundred 

 and six pages, of which three hundred and forty- 

 six are devoted to organic chemistry and the re- 

 mainder to inorganic chemistry. Concise and 

 correct statements regarding the more important 

 data of the various elements and their derivatives 

 are given. No fault can be found with the 

 matter presented. One is impressed with the 

 fact that the most recent chemical literature has 

 been carefully gleaned. It is stated in the pref- 

 ace that when preparing this book the author 

 had mainly in view the needs of medical and 

 pharmaceutial students, and the impression 

 made upon the reviewer, after careful exami- 

 ination of the text, inclines him to the opinion 

 that Prof. Arnold has truly succeeded in mak- 

 ing a valuable ' quiz compend ' for a class of 

 students who study chemistry chiefly as a side 

 issue. The typography and binding are well 

 executed. S. 



SCIENTIFIC JOURNALS. 

 AMERICAN JOURNAL OF SCIENCE. 



The June number opens with an article by 

 TM. Carey Lea, ' On the Color Kelations of 

 Atoms, Ions and Molecules.' This is the sec- 

 ond part of an investigation, the earlier results 

 of which were published in the Journal for May, 

 1895. In the present paper the author dis- 

 cusses first the interaction of ions. It is shown 

 that if a colored substance be formed by the 

 union of a colorless kation with a colorless 

 anion, the color belongs to the molecule only. 

 The colorless ions have so modified each other's 

 vibration periods that selective absorption is ex- 

 ercised. As soon, therefore, as the molecule is 

 divided into ions the color must disappear. 

 Consequently a solvent which is capable of 

 separating the ions gives a solution, which 

 when dilute must be colorless, no matter how 

 intense the color of the compound. This is il- 

 lustrated by the case of the highly colored 

 Sb,S,, which forms colorless solutions because 

 the ions, antimony and sulphur are color- 

 less. 



Furthermore, in regard to the combination of 

 ions, it is shown that two or more similar color- 

 less ions may unite to form colored elementary 

 molecules ; on the other hand, if colored, they 



may unite to form a colorless or white mole- 

 cure or polymer ; or to form a molecule of a 

 wholly different color, as when blue copper 

 ions unite to form red copper. Still, again, 

 two or more dissimilar colorless ions may 

 unite to form a colored molecule, as sul- 

 phur and silver to form black silver sulphide. 

 The use of acid indicators, for example, of lit- 

 mus, is discussed, and it is shown that the 

 change of color on contact with an alkali in no 

 way depends upon dissociation. 



The relation of the subject in general to the 

 classification of the elements is taken up and 

 extended beyond the point where it was carried 

 in the earlier memoir. The failure in certain 

 cases of Mendeleef 's periodic law is remarked 

 upon and it is shown that the relation of ions to 

 the visual rays leads to a classification which is 

 in complete harmony with the chemical char- 

 acteristics of the elements. 



C. C. Hutchins and F. C. Robinson have a 

 paper on the making and use of Crookes tubes 

 to be employed in studying the phenomena con- 

 nected with the Eontgen rays. The authors 

 show that, with suitable choice of material and 

 some skill in glass-blowing, tubes of the most 

 favorable form may be made and exhausted in 

 the laboratory. They have repeatedly made 

 one, exhausted it and used it, all within an 

 hour's time. The particular form of the tube, 

 and the shape and distribution of the electrodes 

 which are most favorable for producing a rapid 

 result are discussed. It is stated that excel- 

 lent impressions of the bones of the hand 

 through thin sheet zinc have been obtained in 

 two minutes. Incidentally some suggestions 

 are given in regard to the best method of pump- 

 ing in order to produce the high degree of ex- 

 haustion called for. 



A. M. Mayer gives the results of researches 

 on the Rontgen rays. He shows, in the first 

 place, that they cannot be polarized by being 

 passed through herapathite, or the iodo-sul- 

 phate of quinine, discovered by Herapath. 

 The details of the experiments leading to these 

 results are given, and incidentally the density 

 of the material was found to be 1. 557. In study- 

 ing the transmission of the rays through certain 

 materials the following results have been ob- 

 tained, taking the amount of transmission 



