'2VS Dr. Schvveigger-Seidel oh the Blue Culuuring-matter 



substances by containing a considerable proportion of iron : 

 L. Gmelin, however, also found iron in the lazuli, and he 

 would not have been disinclined to take the colouring principle 

 for protosulphuret of iron, had not Clement and Desormes 

 shown that there is no iron in the ultramarine. 



Almost at the time when Vauquelin's and Gmelin's inves- 

 tigations of substances resembling lazulite* (which evidently 

 were indebted for their existence to chemical processes nearly 

 related,) raised the possibility of an artificial production of 

 ultramarine almost to a certainty, without, however, giving 

 any clear explanations respecting it, another German che- 

 mist (who has not only enriched the science in so distin- 

 guished a manner, but also the arts by a number of ingenious 

 investigations) found in quite a different way an indication of 

 the colouring-matter in the lazuli, and he would have required 

 but little further investigation to become perfect master of the 

 artificial production of ultramarine. 



By the communication of some experiments on the fuming 

 sulphuric acid, which were published in the year 1815 in this 

 (Schweigger's) Journalf, Doebereiner developed his views on 

 the composition of sulphur, as consisting of hydrogen and a 

 probably metallic body {schxoefdstoff), whence he felt inclined 

 to deduce the blue colour of Vogel's blue sulphuric acid. "And 

 ifV concluded this able chemist, " the colour of the pure sul- 

 phureous substance is really blue, the colour of the ultramarine 

 seems to be solely produced by this substance; and that from 

 potash or soda, sulphur, silica and alumina, under certain con- 

 ditions, a blue similar to the ultramarine, only less brilliant and 

 beautifully clear, may be produced, I have shown a year ago to 

 Professors Gehlen and Schweigger. I have been withdrawn 

 from this investigation by other occupations, but shall soon 

 again devote myself to it, and communicate the results." 

 He, then, was the chemist who for the first time pi'onounced 

 the colouring principle of ultramarine to be sulphur. 



Unfortunately Doebereiner has not again pursued his beauti- 

 ful discovery : it is therefore the more satisfactory that the 

 fact is now confirmed in many journals, with the intelligence 

 which, no doubt, will please the practical chemists, that an- 

 other of our most distinguished German chemists. Professor 

 C. G. Gmelin of Tubingen, has succeeded in the discovery of 

 a proper chemical process for the production of ultramarine. 



• See this (Schweigger's) Joiirnal, vol. xiv. Old Series, p. 325 — 335, where 

 at p. 331 a tabular view is given of the analyses here alliuled to. Let it 

 also be observed that Gmelin found traces of potash besides the soda in 

 the lazuli, and 2 per cent of magnesia. 



t Vol. xiii. Old Series, n. 47G — 484. 



We 



