QA ; REPORT—1863. 
Toping, although coloured a brown-black, was metely a surface-covering, below 
which the powder was colowrless. 
PuospHorus.—Bluish black on surface only, below almost colourless. 
CuLonipE oF Limr.—Deep brown on surface only, below slightly yellow. 
Hyprocutoric Acip.— Grey-pink on surface only, below orange. 
Nirric Aciy.—Dark red-brown, extending slightly into the powder, below 
colourless. 
CarBoNATE OF Iron witH GuacraL Acetic Acip.— Yellowish brown to thick- 
ness of cardboard, below buff: 
LIMESTONE WITH SuLPHuRIC Acip,—Pale brown to thickness of cardboard, 
below slightly stained. 
CARBONATE OF [Ron WITH StLpHuRIC Aci.—Black to depth of § of an inch. 
Nirrovs Acip.—Dark brown more than the eighth of an inch deep, below yel- 
lowish brown. 
Nirric ActD MIXED WITH OzoNE PowpER (both exposed and unexposed ).— 
Blue-black the sixth of an inch deep, below reddish brown. 
The aboye experiments may require modification, yet they show differences so 
striking as to open up a new method of investigating ozone. The action of ozone 
on the dry-powder tests is somewhat analogous to that produced by nitric acid ; yet 
dilute nitric acid, when ten times stronger than the French philosophers declare is 
the proportion present in the air, does not colour the tests. It seems probable that 
whatever colours the tests is always present in the air, as on no occasion has my 
sensitive dry-powder test failed to show its presence, even when test-slips have re- 
mained uncoloured for some days. Its varying intensity may be attributed to cir- 
cumstances acting for or against its visibility. Thus an increase of temperature 
from the increased chemical action should show an increase of ozone. An increase 
in the velocity of air will increase the amount of ozone, because a greater number 
of cubic feet of ozonized air passes over the test in a given time. To a certain ex- . 
tent the increase of moisture will favour the development of ozone, beyond which, 
when the air becomes saturated, a minimum will result. Most ozone at Highfield 
House occurs with a 8. wind, and least with a N.E. wind. The maximum amount 
of ozone is attained when the barometer is at its lowest readings, and the minimum 
when at its highest. This may be owing (and, no doubt, is in part) to the increased 
velocity of a S. wind over that of a N.E. wind, its increased temperature, and 
moisture. Supposing the amount of ozone in a cubic foot of air to be represented 
by 5 at a pressure of 295 inches, ought it not to be more than 5 when this pressure 
is increased, and less than 5 when diminished ?—yet the contrary is shown to result 
in practice. 
On the Connexion that exists between Admiral FitzRoy’s “ Caution Telegrams” 
and the Luminosity of Phosphorus. By Dr. Morrat. 
On a Free Air Barometer and Thermometer. Devised by the Abbé Juannon ; 
exhibited and explained by the Abbé Moteno. 
It consisted of a siphon of about the bore of the tube of a maximum thermo- 
meter, one branch of the siphon open to the air, the other branch furnished with 
two bulbs, one at top for air, the other near the bend at the bottom full of mercury, 
with a little glycerine oil, or other fluid not capable of acting on or absorbing the 
air of the upper bulb, floating on the surface of the mercury. The two bulbs are 
so proportioned in capacity, that the changes of the volume of the air in the upper 
bulb by changes of temperature are exactly compensated by the increased pressure 
of the mercury by the same cause, so that, as far as temperature is concerned, the 
surface of the mercury or glycerine between the bulbs shall remain perfectly fixed 
or unaffected. The branch then between the bulbs becomes a simple sympieso- 
meter or pressure-barometer, while the open straight branch becomes a very 
sensitive thermometer. 
On «a Metallic or Holosteric Barometer. Constructed by M. Navper; 
exhibited and explained by the Abbé Moreno, 
