SCIENTIFIC SUMMAKY. 
201 
ozone, no matter how produced, is rapidly destroyed by a temperature of 
237° Centigrade. An apparatus was fitted up, by means of which a stream 
of atmospheric air could be heated to 260° C. in a globular glass vessel of 
the capacity of five litres. On leaving this vessel, the air was passed through 
a U-tube, one metre in length, whose sides were moistened internally with 
water, while the tube itself was cooled by being immersed in a vessel of 
cold water. On passing atmospheric air in a favourable state through thi& 
apparatus, at the rate of three litres per minute, the test-paper was distinctly 
tinged in two or three minutes, provided no heat was applied to the glass 
globe. But when the temperature of the air, as it passed through the 
globe, was maintained at 260° C., not the slightest action occurred upon the 
test-paper, however long the current continued to pass. Similar experiments 
with an artificial atmosphere of ozone, that is, with the air of a large cham- 
ber containing a small quantity of electrolytic ozone, gave precisely the same 
results. On the other hand, when small quantities of chlorine or nitric acid 
vapour, largely diluted with air, were drawn through the same apparatus, 
the test-paper was equally affected, whether the glass globe was heated or 
not. From this and other experiments Dr. Andrews thinks himself justified 
in concluding that the body in the atmosphere which decomposes iodide of 
potassium is identical with ozone. 
Professor FranMand^s New Method of W %ter Analysis . — At the meeting 
of the Chemical Society, on Jan. 16th, Dr. Frankland read a long and 
extremely interesting paper, in which he detailed the steps of a novel and 
elaborate system of water analysis, whose precision as gauged by the figures 
obtained in the author’s experiments surpasses that of all processes hitherto 
described. We cannot, we regret to think, afford space for an account of the 
whole system, but we will briefly describe the process recommended for the 
estimation of the organic carbon and nitrogen, as it is about the most useful 
point, at least to sanitary chemists. The first step is to expel the carbonic 
anhydride. Sulphuric acid has been found to effect this easily, and for 
many reasons it has been found the most convenient acid. The solution is 
boiled for a couple of minutes with a small quantity of sulphuric acid, and 
then evaporated ; for this purpose hemispherical glass dishes have been found 
far more convenient than platinum. The evaporation is conducted in vacuo, 
and the residue dried at a steam heat. The heat is applied at the top of the 
bell, by means of a current of hot air j applied in this way the water never 
boils. Five samples of water could be evaporated at the same time in the 
apparatus shown to the Society. The residue is mixed with plumbic chro- 
mate and transferred to a combustion tube, the dish being rinsed with the 
chromate ; a layer of pure cupric oxide is also added. The tube is sealed at 
one end and drawn out at the other to about the same size as the tube of the 
Sprengel’s pump which it has to join. The anterior portion of the tube 
(the position of the layer of pure cupric oxide) is heated, and the tube then 
exhausted for five or ten minutes. The combustion is now made, and the 
tube again exhausted, and the resulting gases collected over mercury. A 
gaseous mixture is obtained, containing free oxygen. After absorbing the 
oxygen by pyrogallic acid, the volume of the gaseous mixture is accurately 
measured. The whole of the carbon is obtained in the form of carbonic 
acid, the nitrogen partly as such, with nitric acid and nitric oxide. The 
