Academy of Scieistce, 19 



response, not only from members of this society, but from many other interested 

 observers in distant parts of the United States. I have been under special obliga- 

 tion, the past year, to tlie kiud assistance of the following gentlemen : Mr. B. B. 

 Smyth, of Elliuwood, Barton county ; Prof. John B. Dunbar, of Washburn 

 College ; Dr. A. H. Thompson, of Topeka ; Messrs. J. H. Long and W. H. Carruth, 

 of Lawrence; and L'Abbe Victor A. Huart, of the Seminary of Chicoutimi, Canada. 

 Correspondence has also been opened with other observers too numerous to be 

 enumerated here. The State Medical Society of Kansas was also, at the outset, 

 quite disposed to lend its assistance in prosecuting this investigation, until some of 

 its officers conceived the erroneous idea that the matter had already been made the 

 subject of a report by the American Medical Association, and, of course, to further 

 discuss any problem upon which so august a body had already passed, was quite 

 out of the question ! That such an impression was entirely unfounded is evident 

 from the following letter : 



Philadelphia, October 6, 1876. 

 Prof. Wm. K. Kedzie, 



Dear Sir: The only consideration of Ozone is an attempt to have its amount 

 in the atmosphere noted and published by the Signal Service Bureau. This was a 

 resolution attached to a report in 1875, by Dr. N. S. Davis, of Chicago. 

 Truly yours, 



Wm. B. Atkinson, 

 Permanent Secretary AvieHcan Medical Association. 



The doctors of the State need therefore have had no fear that in giving this mat- 

 ter attention, they would have been guilty of rehearsing an old subject. The test 

 adopted in our observations, has been that known as the " Iodized Starch Paper" 

 test, devised by Schonbein. Ten parts of starch are boiled in 200 parts of distilled 

 water, to which, when cold, one part of potassium iodide is added. This is ap- 

 plied with a fine water brush to strips of unsized paper, which must be dried and 

 preserved in the dark. When small strips of this paper are exposed to the atmos- 

 phere, if ozone be present, it will at once decompose the potassium iodide, setting 

 free the iodine, which in turn combines with the starch, forming an intensely blue 

 compound, at once apparent upon plunging the paper into water. The degree to 

 which the paper is colored thus affords a very fair evidence of the quantity of 

 ozone present in the atmosphere at that time; and may be recorded by comparing 

 it with the color scale, — a scale of color bands upon paper, numbered from one to 

 ten, and varying from the faintest to the deepest blue. The number of the color 

 band to which the paper most nearly corresponds, is then entered in the record as 

 the result of that observation. It is important that the test paper should be ex- 

 posed to the air in a sheltered situation, protected both from strong wind and from 

 direct sunlight, though freely exposed to the air and to diffused daylight. This color 

 test of Schonbein is very far from being perfectly satisfactory in its operatiim or 

 results. It is arbitrary, and indicates only the relative quantity of ozone present 

 in the atmosphere; but it possesses the great advantages of being simple and easily 

 comprehended, and is undoubtedly by far the best for use among general observ- 

 ers. Two series of observations have been conducted: First, the " Day observa- 

 tion," in which the paper is exposed from seven a. m. to two p. m. Second, the 

 " Night observation," embracing an exposure from nine p. m. to seven a. m. The 

 results of these observations have been recorded on blanks printed for the purpose, 

 which have been regularly forwarded to me at the close of each mont!i, the results 

 being carefully tabulated. I have been under many obligations to Dr. H. B. Baker, 

 Secretary of the Michigan State Board of Health, for the loan of similar records of 



