164s Prof. Wilson on M. J. Nickles' claim to be the 



the 'Transactions' of which it was published. It will be suffi- 

 cient here to give an epitome of its contents. The paper was 

 entitled ''' On the Solubility of Fluoride of Calcium in Water, 

 and its relation to the occurrence of Fluorine in minerals, and in 

 recent and fossil plants and animals." It is divided into seven 

 sections. The first, entitled " Introductory Remarks," details 

 the researches of my predecessors, including those to which I 

 have just referred. The second, entitled "Of the Solubility of 

 Fluoride of Calcium in Water," points out, that, contrary to pre- 

 vious belief, this salt is dissolved by pure water, yielding a solu- 

 tion answering to all the tests of lime and of hydrofluoric acid. 

 The third, entitled " Of the presence of Fluorine in Well-, River-, 

 and Sea-Water," confii-ms and extends the observations of pre- 

 vious analysts on the occurrence of a dissolved fluoride in fresh 

 water, and for the first time announces its direct discovery in 

 sea- water, where Middleton and Dana had independently anti- 

 cipated its presence, after finding it invariably in the shells of 

 marine mollusca and in corals. The fourth section, entitled 

 " Of the presence of Fluorine in Minerals," does not call for 

 special notice. The fifth, entitled "Of the presence of Fluorine 

 in Plants," confirms the results of Will of Giessen as to the exist- 

 ence of this element in the ashes of vegetables, and draws atten- 

 tion to plants and to water as the media by which fluorides may 

 be transferred from the soil to animals. The sixth section, en- 

 titled " Of the presence of Fluorine in Animals," commences with 

 the statement, " As there exists, then, a twofold source of fluor- 

 ine for animals, we may anticipate itsoccurrenceiii various parts 

 of their structure;" and thereafter announces, in opposition to 

 the negative results of Dr. Rees, my confirmation of the obser- 

 vation of Berzelius that a fluoride is present in human urine, a 

 result which the great Swedish chemist hailed with satisfaction 

 before his death*, although M. Nickles seems to think that he 

 has been the first to confirm the original assertion. The paper 

 then proceeds to state, " It could not be doubted, after the facts 

 I have detailed, that fluorine would be found in the two great 

 formative liquids of the animal body, blood and milk ; I have 

 found it in both. So far as I am aware, it has hitherto been 

 overlooked in all the analyses that have been made of these 

 liquids ; probably it has not been sought for. I employed the 

 blood of the Ox, and in two cases obtained markings on glass 

 which only became visible when breathed upon, but are then 

 quite manifest. In the third the glass was distinctly though 

 faintly corroded." 



The concluding part of this section is occupied with a criticism 



* Jahres-Bericht, von Jacob Berzelius, 1848, p. 164, which contains a 

 general comment on my researches of 1846. 



