PHILOSOPHICAL TRANSACTIONS. 
I. On the Constitution and Properties of Ozone. By Thomas Andrews, M.D., 
F.R.S., M.R.I.A., Professor of Chemistry in Queens College, Belfast. 
Received May 16, — Read June 21, 1855. 
Among the many interesting bodies which the researches of modern chemists 
have brought to light, few are more remarkable than the substance to which the 
name of ozone has been given, whether we consider its many singular and anoma- 
lous properties, or its intimate relations with the most important and widely-diffused 
element in nature. For the first recognition of ozone and description of its proper- 
ties, we are indebted to the sagacity of Schonbein, to whom the entire merit of the 
discovery unquestionably belongs. His earlier experiments were, however, chiefly 
directed to the elucidation of its properties, and of the conditions under which it is 
formed ; but not being accompanied by quantitative determinations, they did not 
throw any clear light on its actual constitution. The subject has also attracted of 
late years the attention of several very distinguished physical and chemical inquirers, 
among whom I may particularly mention Marignac, De la Rive, Berzelius, Wil- 
liamson, Fremy and Becquerel, and Baumert. 
Schonbein has shown that a body having a peculiar and highly characteristic 
odour and very similar properties is formed under the three following conditions : — 
1. When electrical sparks are pjissed through atmospheric air. 
2. When pure water, or water holding certain acids or salts in solution, is decom- 
posed by the voltaic current, the new substance appearing, along with the oxygen 
gas, at the positive pole. 
3. When certain bodies, and particularly phosphorus, are slowly oxidized at com- 
mon temperatures in atmospheric air. 
Two distinct questions here arise for consideration. Is the same substance pro- 
duced under these different conditions, or has Schonbein included under the name 
of ozone substances having different compositions, although agreeing in some of their 
MDCCCLVI. B 
