ADDITIONAL 



CHEMICAL 



EXAMINATIONS. 



GDI 



It was found exceedingly difficult to free this earth entirely from oxide of iron and magnesia. I suc- 

 ceeded, however, in separating the iron by the following process, so that the solution no longer gave the 

 reaction indicative of iron either with hydrosulphuret of ammonia or ferro-prussiate of potash. The 

 solution was evaporated nearly to dryness, and while still hot a jet of water was thrown on it. By repeat- 

 ing this process several times the oxide of iron was all precipitated, and could be separated by filtration, 

 though the solution passed with extreme slowness through the filter from the fine state of the precipitated 

 oxide of iron. The magnesia was separated by two methods, either by dissolving the earth in hydro- 

 chloric acid, adding sal ammoniac and neutralizing with ammonia, or, by digesting the earth in water 

 acidulated with a few drops of nitric acid. In consequence, however, of the now earth being slightly 

 soluble in sal ammoniac and in dilute nitric acid, some loss is sustained by this method, and therefore it 

 is not applicable to quantitative analysis. 



When thus separated, this earth has the following properties and reaction with reagents. 



It dissolves readily either in hydrochloric or nitric acid, evolving chlorine from the former acid. The 

 solution in hydrochloric acid, when concentrated, has a beautiful pea-green colour, and the salt crystallizes 

 cither of a slightly paler green or a light chrome yellow, depending on the degree of heat at which the 

 evaporation is completed. The peculiar colour of its salts, together with the appearance of the residue 

 left in the analytical process after treating with caustic potash to separate the alumina, was what first 

 attracted my attention to this earth. 



The solution of the earth in dilute hydrochloric acid gives the following reactions with reagents : 



Ammonia, a white, bulky precipitate, only sparingly soluble in sal ammoniac. This is one of the 

 characters which distinguish it from magnesia. 



Oxalate of ammonia, a white precipitate in neutral solutions : another distinction between it and 

 magnesia. 



Oxalic acid, no precipitate until quite neutralized by ammonia. 



Bicarbonate of potash, white precipitate ; apparently slightly soluble in excess. 



Phosphate of soda aud ammonia; the vesicular precipitate with this reagent is quite peculiar, and 

 forms one of the marked characteristics of this earth. If the reagent bo added without disturbing the 

 fluid, a number of little vesicles are formed, which remain distinct, as if each were enclosed in a delicate 

 translucent membrane. 



Ferrocyanide of potash, a white precipitate, with a slight tinge of bluish green, which seemed to be 

 independent of any remaining trace of oxide of iron; perhaps in part due to the colour of the reagent 

 itself. 



Hydrosulphuret of ammonia, a white precipitate. 



Succinate of ammonia, a white precipitate, even in slightly acid solutions. 

 Benzoate of ammonia, the same, with a tinge of yellow. 



Crystals of sulphate of potash inserted in the solution gave but a very slight precipitate, and that only 

 after long standing. 



The precipitate of phosphate of soda is only soluble in a considerable portion of muriatic acid, and is 

 not precipitated by boiling. 



When separated, and still slightly contaminated with magnesia, the earth has a pale flesh-colour, not 

 unlike yttria. When freed from the magnesia, it has more the appearance of powdered, dried albumen. 



The earth differs from alumina aud glucina in being insoluble' in caustic potash. 



From magnesia, in producing coloured salts ; in being only slightly soluble in ammoniacal salts ; in 

 the peculiar vesicular character of the precipitate with jjhosphate of soda; in being precipitated by oxa- 

 late of ammonia. 



From yttria it differs in not giving a precipitate with oxalic acid in slightly acid solutions ; in being 

 precipitated by succinate of ammonia, even before the solution is quite neutral, which prevents this 

 reagent being applied to separate iron from it, as is recommended by Berzelius for separating iron from 

 oxide of yttria. 



It differs from zirconium, in being soluble in nitric and muriatic acids, after ignition. 

 From cerium, in not turning of a brick red after ignition, and in the colour of its salts, which are not 

 amethystine, but shades of green and yellow, except the nitrate, which is almost colourless. 

 The nitrate crystallizes in prisms, which seem to be right rhombic. 

 Its salts, like the corresponding ones of magnesia, are deliquescent. 



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