528 Chronicles of Science. [Oct., 



the British herbarium, and the collection of fruit and seeds, have 

 been re-arranged, and the recent and fossil Conifer se and Cycadese 

 have been examined and arranged. 



The Botanic Garden at Brussels. — The Belgian Government 

 recently purchased the magnificent collection of dried plants of the 

 late Von Martius as the nucleus of a national herbarium. It 

 has more recently concluded the purchase of the Botanic Garden 

 belonging to the Horticultural Society of Belgium ; and has thus 

 commenced the formation of a national establishment intended to 

 rival those of Paris and London. 



5. CHEMISTEY. 



Of all the non-metallic elements, fluorine appears the most dif- 

 ficult to bring under the domain of organic chemistry ; very few 

 compounds of this element with carbon, hydrogen, and nitrogen 

 being known. Dr. K. Schmitt and H. von Gehren have recently 

 succeeded in preparing Fluorbenzoic acid and Fluorbenzol. Fluor- 

 benzoic acid is prepared from diazo-amidobenzoic acid by treating 

 that substance at a high temperature in a platinum basin with 

 hydrofluoric acid. The fluorbenzoic acid thus obtained resembles, 

 as far as its physical properties are concerned, benzoic acid ; it is, 

 however, far more volatile, fuses at 182° C, is difficultly soluble in 

 cold, readily in hot water, and soluble also in ether and alcohol; 

 its aqueous solution exhibits a strongly acid reaction to test-paper 

 and decomposes inorganic carbonates very readily ; the acid does not 

 act upon glass, and is a very fixed substance, which may be even 

 dissolved in concentrated sulphuric acid without decomposition. 

 Fluorbenzol is a crystalline solid, boiling at about 183° C, fusing 

 at 40°, insoluble in water, and specifically heavier than that liquid, 

 readily soluble in ether and alcohol. 



Whilst organic chemistry is aptly called the chemistry of 

 carbon, Drs. Friedel and Ladenburg are engaged in researches 

 which tend to place silicium parallel to the former element. They 

 have succeeded in preparing what they call silico-propionic acid, a 

 compound wherein a large percentage of the carbon of propionic 

 acid is replaced by silicium. The physical aspect and many of 

 the properties of this body are akin to silica; but it is a com- 

 bustible substance, insoluble in water, but soluble in a hot and 

 concentrated solution of caustic potassa. M. Dumas observed, in 

 reference to this paper, that it is not impossible that there exist in 

 nature organic compounds of silica, a remark which gave rise to 

 some observations on Dr. Friedel's ' Memoir,' by P. Thenard. The 

 author begins with stating that M. Dumas is quite right, and 



