Annual Report of the Council. li 



After his graduation, Moissan from 1879 to 1883, devoted 

 himself at first chiefly to the study of the compounds of chromium, 

 investigating in particular the chromous salts and perchromic 

 acid. Subsequently, in the laboratory of Debray, and with the 

 active encouragement of Troost and Friedel, he commenced his 

 researches upon fluorine which culminated in 1886 in the 

 isolation of this element. 



The difficulties, which had baffled the experimental ability 

 of Humphrey Davy, Faraday, Fremy, and many others, were 

 overcome, and fluorine itself was presented to us. That this 

 may justly be considered to be one of the greatest achievements 

 of experimental chemistry in the nineteenth century can be 

 judged not so much by the brilliant result attained as by the 

 display of indomitable pluck and perseverance which assured the 

 successful issue. 



After a number of fruitless but well-planned attempts to 

 separate the element from its compounds with silicon, 

 phosphorus, and arsenic, Moissan, on June 28th, 1886, com- 

 municated to the Academy of Sciences, the first details of his 

 experiments on the electrolysis of anhydrous hydrofluoric acid 

 containing potassium bifluoride. The definite proofs of the 

 identity and elementary nature of fluorine were presented in the 

 following month, whilst, on November 8th, Debray reported to 

 the academy the complete conviction of the section of chemistry 

 of the validity of the experiments. 



From 1886 to 1891, Moissan published numerous papers on 

 the chemical and physical properties of fluorine and on many 

 of its compounds, the careful and detailed nature of the 

 investigation being characteristic of all his work. 



Attention should also be directed to the fact that in 1897, in 

 conjunction with Sir James Dewar, fluorine was liquefied ac the 

 Royal Institution. The construction of an apparatus of copper 

 in 1899, to replace the expensive platinum vessels previously 

 employed, simplified the preparation of the element, and the 

 discovery that dry fluorine free from vapours of hydrofluoric 



