OZONE AND ANTOZONE. LaS 
liable quantitative test. The largest proportion with which the air has been 
artificially loaded with this substance amounts to too Of its volume. 
Ozone may be determined quantitatively by ascertaining the amount of 
iodine liberated from iodide of potassium; by determining the quantity of pe- 
roxide of silver which it produces; or by finding the proportion of indigo solu- 
tion which it decolorizes. But this kind of test has never been applied toa 
great extent in determining the atmospheric ozone in long series of observa- 
tions, owing to the difiiculty and labor of applying it. 
A large volume of air brought slowly to act upon a small proportion of the 
reagent is necessary for this purpose. In aspirating twenty-four litres of external 
air ue a period of two and a half hours, poacepirating its action upon a 
circle 3), of an inch in diameter on a delicate iodide of potassium starch paper, 
I was unable to detect the slightest ozone reaction, although a slip of similar 
paper exposed all day to the free atmosphere was colored sensibly. 
The ordinary mode of observing ozone in the atmosphere consists in ascer- 
taining the amount of color produced upon paper containing iodide of potas- 
sium and starch, using precautions against the bleaching effect of the light 
upon the iodide of starch developed by the ozone. A scale of shades of color 
is employed for determining, by comparison, the proportion of the gas in ques- 
tion present in the atmosphere. Boehm found that this test, prepared from 
the same recipe by different persons, gave varied results. According to Osann’s 
formula, thirty-two grains of starch are rubbed in a mortar, with the same 
_ quantity of cold water ; three grains of iodide of potassium are then dissolved in 
four ounces of boiling water, and the solution is added to the starch and well 
incorporated with it. After boiling once more, the test is cooled and placed in 
a bottle for use. When reagent paper is required, slips of Swedish filtering 
paper are shaken up with the starch liquid, and then dried. ‘This paper is in- 
stantly colored of a deep shade of blue when exposed to the ozonized air of a 
bottle containing phosphorus and a little water. Exposed during the night to 
the atmosphere, the coloration by ozone ig very decided. 
In the ordinary atmospheric ozone observations the velocity of the air-cur- 
rent which traverses the reagent paper intluences the result by bringing a greater 
proportion of ozone upon the test ina given time. ‘The determinations which 
have been hitherto made are very vague, unsatisfactory, and yield but rude 
comparative results as to the subject in question. 
Notwithstanding this difficulty, theories have not been wanting as to the in- 
fluence of ozone upon the health. The oxidizing action of ozone upon organic 
substances as shown by Gorup von Besanez, the phenomena of ozone carriers, 
such as oil of turpentine, platinum sponge, and the blood corpuscules, have 
facilitated the formation of such theories. 
Dr. Smallwood, in a long series of observations upon the atmosphere of Can- 
ada during the prevalence of the cholera and at other times, favored the in- 
ference of a deficiency of ozone during the epidemic. 
Dr. Moffatt concluded, from a large number of observations in England, that 
the ozone in the atmosphere plays an important part in controlling or prevent- 
ing epidemics, which it effects by removing the infectious matter from the air. 
During the prevalence of the cholera at Newcastle, in 1853, this gas was at 
its minimum. From August 24 to September 11, 1854, when the disease was 
at its height in London, ozone was observed only once, and then in but small 
quantity. On the 10th September a south wind prevailed, by which the ozone 
was found to increase, and the cholera cases diminished. During the Crimean 
war the surgeons of the I’rench army established the following facts : 
1. In proportion as the ozonoscopic papers were more colored in the air, the 
more numerous were the sick taken to each of the hospitals. 
2. When the temperature was higher, there were fewer sick and fewer deaths. 
