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from which Vegetables derive this Element; by George Wilson, M.D.' 

 The author commenced by stating that the earliest observer of the 

 presence of fluorine in plants was Will, of Giessen, who found traces 

 of it in barley, the straw and grain of which were analyzed together. 

 The author reported to the Botanical Society, some four years ago, 

 the results of his earlier researches into the distribution of this element 

 throughout the vegetable kingdom, which were not very numerous or 

 very encouraging. One reason of this was the small extent to which 

 fluorine occurs in plants ; another, and practically as serious a reason, 

 was the difficulty of separating and recognizing fluorine when accom- 

 panied by silica. The presence of this body in a plant, besides greatly 

 complicating the investigation, rendered the employment of platina 

 vessels essential, and thus limited the amount of material which could 

 be subjected to examination, besides making it difficult or impossible 

 to observe the progress of an analysis. 



The author then stated that in the course of some recent investiga- 

 tions into the presence of fluorine in siliceous rocks, he had succeeded 

 in devising a process which was also applicable to plants, and could 

 be carried on in the ordinary glass vessels of the laboratory. The 

 process in the case of plants was as follows : — The plant under exami- 

 nation was burned to ashes as completely as possible. The ashes 

 were then mixed, in the cold, with oil of vitriol, so as to secure the 

 decomposition of the salts of volatile acids present. The mixture was 

 then transferred to a retort, or flask, provided with a bent tube dip- 

 ping into water, and the liquid raised to the boiling point, when fluo- 

 rine, if present, was evolved in combination with the silicon of the 

 silica, as the gaseous fluoride of silicon, which dissolved in the water, 

 with separation of some gelatinous silica. The resulting solution was neu- 

 tralized with ammonia, and evaporated to complete dryness, when the 

 whole of the silicon passed into the condition of insoluble silica, and 

 water dissolved the fluoride of ammonium. The solution of this fluo- 

 ride could then be dried up and moistened with sulphuric acid, when 

 hydrofluoric acid was evolved, which might be made permanently to 

 record its presence, by causing it to etch glass in the usual way. The 

 author has in the meanwhile applied this process almost solely to the 

 stems and trunks of plants, especially to those containing siHca, re- 

 serving for subsequent investigation their other organs, especially their 

 seeds and fruits. The following were the results obtained : — 



