ON EIGHT BALLOON ASCENTS IN 1862. 483 
§ 9, Exzcrricat Srare or THE ATMOSPHERE. 
In the ascent on July 17, an electrometer, kindly lent by Professor W. 
Thomson, of Glasgow, was used. Care (according to the instructions from 
Professor Thomson) was taken to discharge the electricity from the balloon 
on leaving the earth, and a charge of negative electricity was given to the 
instrument, and it read 59°, which we may call the balloon-reading. The 
instrument leaked a little, and it was necessary at every experiment to re- 
determine the balloon-reading. The following are the results of the ob- 
servations :— 
Map doo | Ra Tee a ge 
as 1ss00 te. {Bien a 
At 15,700 fect. . | Groctrcity of the air. 68 
At 19,500 feet... rectrivity of the ait 1. 61 
118300 i 4 
Balloon-reading ¥..... 58 
#4,23,000 fret, . Electricity of the air .. 58+ 
Now as these observations were made under the balloon, and the readings for 
the air were large negative readings always, it implies that the air was 
charged with positive electricity, but becoming less and less in amount with 
increasing elevation, till at the height of 23,000 feet the amount was too 
small to measure but was of the same kind. It is impossible therefore to 
say whether at higher elevations there would have been no electricity, or 
whether it would haye changed to negative. I wish, however, to speak 
guardedly on this subject, and would regard these observations as indications 
only. I pledge myself no further than that all the directions given to me by 
Professor Thomson were followed, and that the readings are correct. 
On tHe Oxycentc Conpition oF THE ATMOSPHERE. 
On July 17th the test papers, both by Moffat and Schonbein, continued 
untinged by colour throughout the whole flight of the balloon, and the same 
result was found during the ascent on July 30. 
After these ascents I received the following letter from Dr. Moffat :— 
“ Hawarden, August 4th, 1862. 
Dear Mr. GuaisHEr, 
“Tn the Times of Saturday last I observed, in your report of meteorological 
observations taken during a balloon ascent from the Crystal Palace on July 30th, 
that ‘test ozone papers were not coloured, and no ozone was noticed in the 
ascent from Wolverhampton.’ This is remarkable, seeing that ozone increases 
in quantity directly with increase of elevation on the earth’s surface. The 
degree of coloration of test papers varies with the humidity of the atmosphere. 
Dry air retards the decomposition of the iodine of potassium, and very moist 
air removes the iodine when decomposition has taken place. It does not 
‘appear, however, in the observations, that the degree of humidity on the day 
of ascent was in any way unfavourable to the decomposition of the iodine, or 
the development of the brown colour on the test papers. 
2x2 
