Mr. E. J. Lowe on Ozone. 233 



There are advantages in the powders over the ordinary tests. They 

 are more sensitive, and therefore more rapidly acted upon ; they re- 

 tain their maximum colour, not afterwards fading, as with the tests 

 of Schonbein and Moffat. (However, my calico and porous-paper 

 tests are not nearly so liable to fade, owing to the solution penetra- 

 ting into the fabric used, instead of being merely a surface-covering.) 

 There is also a more important advantage still to be mentioned from 

 the use of powders. By the aid of powder tests we shall ascertain 

 what colours the tests ; in the experiments it was found that a dif- 

 ferent colour was imparted to the powder, and that the colour pene- 

 trated deeper with some substances and acids than with others, so 

 that differences of effect took place, from which the different mate- 

 rials used might be recognized. Thus : — 



1 . Iodine, although coloured a brown-black, was merely a surface 

 colouring, below the powder remained colourless. 



2. Phosphorus, bluish black on the surface only, below almost 

 colourless. 



3. Chloride of lime, deep brown on the surface only, the powder 

 below slightly yellow. 



4. Hydrochloric acid, grey-pink on the surface only, the powder 

 beneath orange. 



5. Nitric acid, dark-red brown extending slightly into the powder, 

 beneath that colourless. 



6. Carbonate of iron with glacial acetic acid, yellowish brown to 

 the thickness of cardboard, below that buff. 



7. Limestone with sulphuric acid, pale brown to the thickness of 

 cardboard, beneath slightly coloured. 



8. Carbonate of iron with sulphuric acid, black to the depth of a 

 quarter of an inch. 



9. Nitrous acid, dark brown more than the eighth of an inch 

 deep, beneath yellowish brown. 



10. Nitric acid mixed with exposed ozone powder, blue-black to 

 the sixth of an inch deep, below that reddish brown. 



1 1 . Nitric acid mixed with unexposed ozone powder, blue-black 

 to the sixth of an inch deep, below that reddish brown. 



These experiments may require some modification, yet they point 

 out the fact that striking differences are apparent, differences which 

 must open up a new method of investigating ozone. 



Not only have the tests hitherto used been made without due re- 

 gard to the pureness of the chemicals and fitness of the material 

 used, but the paper box in which they have been kept is not sufficient 

 for their perfect preservation ; a dark, dry, air-tight box is essential ; 

 and this should not be opened in a room where there is iodine, 

 chlorine, nitric acid, phosphorus, hydrochloric acid, or other che- 

 micals likely to be injurious to the tests. I am now manufacturing the 

 tests, which will be distributed by Messrs. Negretti and Zambra, and 

 I have constructed a proper box in which in future they will be sent. 



" On the Equations of Rotation of a Solid Body about a fixed 

 Point." By William Spottiswoode, M. A., F.R.S. 



"On the Fossil Human Jawbone recently discovered in the Gravel 

 near Abbeville." By W. B. Carpenter, M.D., V.P.B.S. 



