610 PRINCIPLES OF CHEMISTRY 



rence in nature, to the absence of any especially distinct individual 

 properties, and to the possibility of foretelling them to a certain 

 extent on the basis of the periodic system of the elements given in 

 the following chapter, and owing to the brevity of this treatise, we 

 will not linger long over the compounds of beryllium, and will only 

 observe that the individuality of the compounds of beryllium was 

 pointed out in 1798 by Vauquelin, and that metallic beryllium was 

 obtained by Wohler and Bussy. "VVohler obtained metallic beryllium 

 (like magnesium) by acting on beryllium chloride, BeCL 2 , with potassium. 

 Metallic beryllium has a sp. gr. 1-64 (Nillson and Pettersson). It is 

 very infusible, melting at nearly the same temperature as silver, which 

 it resembles in its white colour and lustre. It is characterised by the 

 fact that it is very difficultly oxidised, and even in the oxidising flame 

 of a blow-pipe is only superficially covered by a coating of oxide ; it 

 does not burn in pure oxygen, does not decompose water at the 

 ordinary temperature or at a red heat, but gaseous hydrochloric acid 

 is decomposed by it when slightly heated, with evolution of hydrogen 

 and development of a considerable amount of heat. Even dilute 

 hydrochloric acid acts in the same manner at the ordinary temperature. 

 Beryllium also acts easily on sulphuric acid, but it is remarkable that 

 neither dilute nor strong nitric acid acts on beryllium, which seems to 



in solution. The solubility of the beryllium oxide already clearly indicates its feeble 

 Imsic: properties, and, as it were, separates this oxide from the class of the alkaline earths. 

 But on arranging the oxides of the above-described metals of the alkaline earths accord- 

 ing to their decreasing atomic weights we have the series 



BaO, SrO, CaO, MgO, BeO, 



in which the basic properties and solubility of the oxides consecutively and distinctly 

 decrease until we reach a point when, had we not known of the existence of the beryllium 

 oxide, we should expect to find in its place an oxide insoluble in water and of feeble basic- 

 properties. So also in the series of the metals of the alkalis the basicity of lithium oxide 

 is distinctly more feeble than sodium and potassium oxides, and lithium carbonate is 

 insoluble in water. 



Another characteristic of the salts of beryllium is that they give a gelatinous pre- 

 cipitate with aqueous ammonia, which is soluble in an excess of ammonium carbonate, 

 like the precipitate of magnesia ; in this beryllium oxide differs from the oxide of 

 aluminium. Beryllium oxide easily forms a carbonate which is insoluble in water, and 

 resembles magnesium carbonate in many respects. Beryllium sulphate is distinguished 

 by its considerable solubility in water thus, at the ordinary temperature it dissolves 

 in an equal weight of water ; it crystallises out from its solutions in well-formed crystals, 

 which do not change in the air, and contain BeSO 4 ,4H.X). When ignited it leaves 

 beryllium oxide, but this oxide, after prolonged ignition, is re-dissolved by sulphuric acid, 

 whilst aluminium sulphate, after a similar treatment, leaves aluminium oxide, which is 

 no longer soluble in acids. With a few exceptions, the salts of beryllium crystallise with 

 great difficulty, and to a considerable extent resemble the salts of magnesium ; thus, for 

 instance, beryllium chloride is analogous to magnesium chloride. It is volatile in an 

 anhydrous state, and in a hydrated state it decomposes, with the evolution of hydro- 

 chloric acid. 



