466 Prof. Schonbein on the Allotropic States of Oxygen ; 



perties. The carbonic acid did not appear to be in excess of the 

 lime. 



The second portion was very white and soft ; after being dried 

 in vacuo it did not give off water when heated at 100° C. It 

 dissolved readily in hydrochloric acid with formation of gelati- 

 nous silica. 



The results of analysis were as follows : — 



Silicic acid 4*3 1 



Alumina 59*08 



Water 35-03 



Carbonate of lime, and loss . . . 1*58 



100-00 



This is almost identical with one of the specimens from Hove. 



Altogether these hydrated silicates of alumina, many of which 

 have been analysed and described under the names of allophane 

 and collyrite, appear to form a series in which the silicic acid 

 varies greatly in proportionate amount. They may be viewed 

 as a hydrated silicate of definite composition, combined with 

 indefinite amounts of the native hydrate of alumina, A1 2 8 , 

 3HO, Gibbsite. But what is this definite silicate? Collyrite, 

 2(Al 2 3 )Si0 2 , 9HOplus6(Al 2 3 , 3HO), would give numbers 

 almost identical with those of the last analysis recorded above ; 

 but collyrite itself might be viewed as allophane plus some 

 equivalents of hydrate of alumina, and Mr. Northcote views 

 allophane as a still higher silicate combined with different pro- 

 portions of the hydrate. All these formulae might also be ex- 

 pressed as Dr. Odling's ortho- silicate, Al 4 SiO 4 , plus more or less 

 hydrate of alumina, plus more or less water ; but not one of these 

 methods of expression appears to possess any such preponderating 

 advantage as to lead to the conviction that it represents the 

 true composition of the mineral under its various phases. 



LXIV. On the Allotropic States of Oxygen ; and on Nitrification. 

 By Professor C. F. Schonbein*. 



I HAVE been busily occupied with my favourite study, and 

 have found out several new facts regarding the allotropic 

 states of oxygen, their changeability one into another, and nitri- 

 fication, and I am inclined to believe that the results obtained 

 are not quite void of scientific interest. 



After many fruitless attempts at isolating ozone from an 



" ozonide", I have at last succeeded in performing that exploit ; 



and have also found out simple tests for distinguishing with the 



greatest ease ozone from its antipode, " antozone." As to the 



* Extracted from a Letter to Professor Faraday. 



