164 Scientific Intelligence. 



4. The Conductivities of some Double Salts as Compared with 

 the Conductivities of Mixtures of their Constituents. — F. Lindsay 

 has made a series of experiments from which he draws the con- 

 clusion that the conductivity of a double salt in concentrated 

 solution is slightly less than that of a mixture of the constituents 

 having the same concentration. In other words, he infers that it 

 makes a difference in conductivity whether the constituents of a 

 double salt have been in actual combination in the solid state or 

 not before they are dissolved. The work, coming as it does from 

 the laboratory of Professor H. C. Jones of Johns Hopkins Uni- 

 versity, deserves careful attention, but the conclusions are so 

 incredible that it seems easier to assume that the results are due 

 to experimental errors than that they are true. It must be ad- 

 mitted that the work was evidently done with great care, and that 

 three different double salts gave differences in the same direction ; 

 but these differences are small, and the results, being entirely con- 

 trary to the modern ideas of equilibrium in solution, will hardly 

 gain general acceptance without the most convincing confirma- 

 tion. — Am. Chem. Jour., xxv, 62. h. l. w. 



5. Cause of the Loss in Weight of Commercial Platinum 

 when Heated. — Having observed unusual losses in the weights of 

 platinum crucibles upon the introduction of blast from a blowing- 

 engine into a new laboratory, R. W. Hall has made some import- 

 ant observations on the subject. He finds that strongly oxidiz- 

 ing flames greatly increase this loss. Where a crucible was 

 placed high up in a blast-lamp flame the loss was 1*0 mg. per 

 fifteen minutes, while lower down where the temperature was 

 higher the loss was only one-fourth as great. The author does 

 not find that the loss decreases after repeated ignition, as has 

 been previously supposed, and various kinds of crucibles, old and 

 new, of soft, comparatively pure platinum, and one of platinum- 

 iridium alloy gave about the same results. Experiments were 

 made by heating platinum wires by means of an electric current 

 in a glass tube through which various gases were passed. Carbon 

 monoxide, carbon dioxide and hydrogen gave little or no losses, 

 while in air and oxygen the loss of platinum was very rapid, and 

 mirrors were produced in the tube. An examination of one of 

 the mirror-like deposits showed that the volatilized metal does 

 not dissolve in aqua regia as rapidly as the original wire, hence 

 it is inferred that certain elements are fractioned out of the 

 impure platinum. As an explanation of the results, the sugges- 

 tion is made that a volatile oxide of platinum is formed. — Jour. 

 Am. Chem. Soc, xxii, 494. h. l. w. 



6. An Elementary Treatise on Qualitative Chemical Analysis ; 

 by J. F, Sellers. 12mo, pp. vii, 160, Boston, 1900 (Ginn & 

 Company). — The author of this little book has aimed to avoid 

 the two extremes of fullness and brevity. His objection to the 

 latter in books where the material is condensed into " tables " 

 and " schemes " is undoubtedly well founded, and these unde- 

 sirable features are avoided. The practical part has been care- 



