166 On the Discovery of Fluorine in the Blood. 



*< On the presence of Fluorine in the stems of Granaineae, Equi- 

 setacese, and other Plants, with observations on the sources from 

 which vegetables derive this element." In this communication, 

 read July 8, 1852, I reported the results of an examination of 

 twenty-four plants or vegetable products, in twelve of which 

 fluorine was found. It will suffice to state, in reference to both 

 papers, that their object is to point out and illustrate by exam- 

 ples, methods of readily discovering fluorine in circumstances 

 which previousl)'^ rendex'cd its detection difficult. 



The more perfect of the two processes has been applied with 

 success by Professor Hofmann to the detection of fluorine in the 

 mineral waters of Harrogate; and Freseniua has introduced it 

 into the last edition of his ' Qualitative Analysis*.' 



The researches thus referred to have been chiefly published in 

 the ' Transactions ' of this Society, and of the British Association, 

 but have been brought in part before the Chemical Society of 

 London. They are known in Germany, Denmark, Sweden and 

 America, and have been referred to by many authors in thia 

 country. It is reasonable, accordingly, to infer that some know- 

 ledge of them has reached Paris ; and it might have been supposed 

 that they had not altogether escaped the notice of M. Nickles, 

 whose name appears on the title-page of the Journal de Phar- 

 maeie et de Chimie, as editing the department of that work entitled 

 " Une revue dea Travaux Chimiques publics a I'Etranger," 



I bring no charge, however, against M. Nickles. In these 

 days of multiplied monographs it would be unjust to blame any 

 man for ignorance of a single series of special researches. Never- 

 theless, seeing that this author's name appears on the title-page 

 of the Journal de Pharmacie side by side with those of our Vieo» 

 President Dr. Christison, as its Edinburgh Correspondent, and 

 of Dr. Redwood, the Secretary of the Cavendish Society, as ita 

 London Correspondent, the countrymen of M. Nickles may think 

 themselves entitled to quote the legal maxim, *' de non apparen» 

 tibus et de non existentibus eadem ratio," and to infer that what 

 of reputed English science is not known to him, does not exist 

 to be known. Whilst, therefore, I wish M. Nickles all succegg 

 in extending our knowledge of the organismal distribution of 

 fluorine, I ask from him, now that he is made aware of the fact, 

 acknowledgement of my priority in reference to the discovery 

 which he specially claims, and of the other discoveries which the 

 papers referred to announce. 



* Fourth edition of the English translation, 1855, p. 134, stated by its 

 editor, Mr. J. L. Bullock, to correspond with the eighth German edition. 

 The process essentially consists in heating the silicated fluoride with oil of 

 vitriol, and condensing the gaseous fluoride of silicon in aqueoun amnioikia, 

 which after evaporation, re-solution in water, and desiccation, yields fluOfide 



