of Lapis Lazuli, aiul on artificial Ultramarine. 2i7 



superintendent of a manufactory of sulphuric acid and soda, 

 found, on breaking up the hearth of one of his smehing fur- 

 naces for soda, in the foundation of it, a blue substance which 

 as long as the hearth had been built of brick, and not of sand- 

 stone as it was then, he had never noticed*. Vauquelhi on ex- 

 amining this substance found it greatly to resemble the lazure- 

 stone, and the analysis also indicated alumina and silica united 

 with soda and sulphite of lime, but at the same time with iron 

 and sulphuretted hydrogen, from which latter components in 

 connection with alkali Vauquelin felt inclined to deduce the 

 blue colour of this substance as well as of the lapis lazuli f. 

 Soon after L. Gmelin examii:ied a volcanic product thrown 

 out by Vesuvius, which Breislak (in his Voyages daiis la Cam- 

 panie) mentions as a seventh kind of lazulite, and which was 

 afterwards classed by Bruun Neergard with the hauyn|. 

 Nevertheless this mineral seemed to agree in its external cha- 

 racters more with the lapis lazuli than with the hauyn, which 

 induced L. Gmelin to repeat the analysis of lapis lazuli at 

 the same time, and to compare the results of these analyses 

 with those he had recently obtained from the chemical investi- 

 gation of the hauyn §. The result was, that the blue volcanic 

 product above mentioned had in reality a great similarity with 

 the lazure-stone even in its chemical composition. But the same 

 observation was also applicable to the hauyn, which seemed to 

 differ from the lazure-stone, essentially, only by a proportion- 

 ately great quantity of sulphuric acid, and by its containing 

 potash instead of the soda found in the lazure-stone. The lat- 

 ter, however, was also the case in the blue volcanic mineral, 

 by which the latter seemed again more closely related to the 

 hauyn than to the lapis lazuli, or at least to form an interme- 

 diate link between the two minerals. This induced L, Gmelin 

 to arrange the lazuli, containing soda, with the hauyn, contain- 

 ing potash, as species or subspecies nearly allied, but to con- 

 sider the blue mineral, under the name of earthy hauyn, as 

 a mere variety of the common, called granular hauyn. In 

 other respects the volcanic product differs from the two other 



* According to a verbal communication of Dr. W. Weissner, the admi- 

 nistrator Herrnian at Hchonebeck liad niaile a similar discovery some years 

 ago, and declared tiie siil)stance to be an ultramarine produced by a che- 

 mical process. Perha|)s we ought also to add to this the blue colouring- 

 iiiatler which at times dyes the calcined potash a beautiful lazure blue, 

 and which has been usually attributed to metallic oxides or finely divided 

 carbon. 



t Compare this (SchwciggcrS:) JoudkiI, vol. xiii. Old Series, p. 486, &c. 

 and vol. xiv. p. XV.\. yinii. dcChim. torn. Ixxxix. p. 88. Thenard, toni. ii, 

 p. 71^- Fcchncr, ii. p. 418. 



\. Jiiuni. (leu Aliiics, No. 12."). , 



§ Obscrvalioncs Geognoslica; ct Chctiiica- dc Uaiii/iia, &c. 



subbtances 



