The IOWA SYSTEM of QUALITATIVE ANALYSIS without HYDROGEN JACOB CORNOG The State University of Iowa, I o w a City, Iowa
W
E WERE prompted to undertake a study of ways andmeans that might be used to decrease or eliminate the use of hydrogen sulfide in our freshman laboratories of qualitative analysis both for the sake of our own comfort and for the sake of the comfort of our colleagues and neighbors who objected to the hydrogen sulfide .laden fumes that not infrequently drifted to their offices and research rooms. We considered semimicro qualitative analysis as a solution of our problem but were deterred in adopting it because we lacked both the necessary special apparatus and the suitably qualified instructional st& needed to initiate such a plan in classes that aggregate about five hundred students annually. Further, semimicro qualitative analysis was not as well developed in this country in 1932, when we began our search, as i t is today. Even today we do not know of many large classes in freshman qualitative analysis that are using semimiao methods. So we turned to non-hydrogen sulfide systems as a possible source of relief. Our search in the literature yielded the references shown a t the end of this paper. It also showed that dissatisfaction with hydrogen sulfide as well as attempts a t formulating non-hydrogen sulfide systems are not new phenomena. Himly (8) in 1842 speaks of hydrogen sulfide as "a headache-producing stench" and proposes sodium thiosulfate as a substitute for hydrogen sulfide in qualitative analysis. During the past five years we have formulated in mimeographed books seven different systems of non-hydrogen sulfide qualitative analysis and tried them in our classes. The latest of these systems, which we call the "Iowa System" as a distinguishing name, has been used during one semester with a class of three hundred students with reasonably satisfactory. results. The remainder of this paper contains a historical review of the subject of qualitatve analysis, a general discussion of non-hydrogen sulfide systems, and an outline of the Iowa System in its current form. HISTORICAL REVIEW
We found that the classical, widely used hydrogen -
* Presented as a part of the syn~pusiumon Qualitative Analysis hcforc the Division of Chemical Kducatiou at the Fourteenth hlidncst I
