38 Gooch and Kreider — Detection of All-aline 



Art. VII. — The Detection of Alkaline Perc/dorates asso- 

 ciated with Chlorides, Chlorates, and Nitrates ; by F. A. 

 Gooch and D. Albert Kreider. 



[Contributions from the Kent Chemical Laboratory of Yale College — XXXIL] 



Though perchloric acid in the free state is an exceedingly 

 active body, its combinations with alkaline metals are, as is 

 well known, so characterized by inertness toward ordinary re- 

 agents that in order to effect its detection it has been cus- 

 tomary to place dependance either upon the insolubility of the 

 potassium salt in alcohol, or upon tests for the corresponding 

 chloride derived by ignition. 



In experimenting at high temperatures upon mixtures of 

 potassium perchlorate with salts of the halogens we have found 

 it possible to effect the liberation of the halogen to a greater or 

 less degree by the oxygen of the perchlorate, but the amount 

 thus evolved has never been sufficiently complete or regular to 

 warrant the application of the reaction to the quantitative 

 determination of the perchlorate. In two parallel experiments, 

 for example, a mixture of the double chloride of aluminum 

 and sodium with 0*05 grm. of potassium perchlorate evolved 

 in fusion in a tubulated flask (which was fitted by a ground 

 joint to an inlet tube carrying a constant current of carbon 

 dioxide and connected with Will and Yarrentrapp absorption 

 bulbs filled with a solution of potassium iodide), an amount of 

 chlorine corresponding to 0*0482 grm. and 0*0460 grm. of the 

 perchlorate. A similar experiment conducted in an atmo- 

 sphere of hydrochloric acid gas and carbon dioxide in mixture 

 yielded chlorine amounting to 0*0477 grm. of the perchlorate. 

 Fusion of the perchlorate with cadmium iodide resulted in the 

 liberation of much oxygen accompanying the iodine, and a 

 mixture of zinc chloride with potassium iodide (melting at 

 about 200° C), yielded a large evolution of oxygen which was 

 somewhat diminished but not wholly prevented when manga- 

 nese chloride was included in the mixture. A series of 14 

 experiments in which mixtures of the perchlorate with potas- 

 sium iodide were treated with meta-phosphoric acid (made by 

 heating the syrupy ortho-acid to 360° C.) in an atmosphere of 

 carbon dioxide showed deficits in the amounts of iodine 

 evolved amounting to 1*7 per cent on the average between 

 extremes of 3*6 per cent in excess and 7*7 per cent in de- 

 ficiency, and these particular experiments doubtless point to a 

 more complete utilization of the oxygen of the perchlorate 

 than was actually attained owing to the inevitable partial de- 



