434 Mr. Sowerby on Diasporc. [June, 



ments to a critical examination by the blowpipe ; and he has 

 favoured me with the following account of his experiments. He 

 will probably take advantage of this opportunity to complete a 

 new analysis of this mineral, which he will communicate to you. 

 I am, Sir, yours, &c. 



G. B. SOWERBY. 



Examination of the above by means of the Blowpipe. By J. G. 

 Children, FRS. L. & E. FLS. &c. &c. 



Specific gravity = 3-205, which is probably a little too light, 

 as some very minute air bubbles adhered to the specimen after 

 immersion in water which I could not completely detach from it. 



Alone in a glass tube decrepitates violently, splitting into 

 minute fragments with a sudden explosion. At first but little 

 moisture is given off, but when the bottom of the tube is nearly 

 red-hot, abundance of water condenses in the upper part. The 

 water has no effect on blue litmus paper. The assay loses its 

 colour, more or less, by heat ; and frequently becomes milk- 

 white on the surface : the fragments do not brown moistened 

 turmeric paper. 



Alone in theforcepSy ovon chaixoal, it is infusible. 



With soda, on the platina wire, it gives an opaque globule of a 

 <iirty pearl colour, incHning to yellow, in the oxidating flame. 

 In the reducing flame the globule is almost black externally ; 

 internally dark-grey, inclining to brown. The assay in this expe- 

 riment was pulverized ; soda has scarcely any action on a frag- 

 ment. 



With borax, on the platina wire, in the oxidating flame, a 

 fragment of the assay dissolved with difficulty in a large propor- 

 tion of the flux into a perfectly transparent glass, which was 

 yellow, while hot ; quite colourless, cold. In the reducing 

 flame, the glass retained its transparency, and was colourless 

 both hot and cold. 



With salt of phosphorus y on platina wire, in the oxidating 

 flame, the pulverized assay dissolves slowly into a perfectly 

 transparent glass, which is deep-yellow, while hot, quite colour- 

 less cold. In the reducing flame, the glass is colourless both 

 hot and cold. No silica skeleton nor residuum is left, nor does 

 the glass become opaque by flaming with either of the two last 

 fluxes. 



With fiitrate of cobalt, a fine deep-blue colour. 



With boracic acid and iron, no trace of phosphoric acid. 



Berzelius states that the fragments of a small piece of 

 Lelelievre's diaspore, " heated to slight redness,*' restore the blue 

 colour of reddened litmus paper. (Use of the Blowpipe, p. 227.) 

 I did not, however, find this to be the case, and therefore Mr. 

 Sowerby's mineral perfectly agrees in all its blowpipe characters 

 with the diaspore of Lelievre. 



