On Selenium from Lukamtz in Bohemia. 83 



The parenchymatous appears formed, in the outset, of de- 

 tached particles which unite and form utricles; so that it 

 assists in the process of increase in every direction. This 

 is the only substance which is susceptible of a green co- 

 lour. 



7. The sap is the food of plants. 



It is pumped up, in the form of moisture, by the roots, and 

 it becomes exposed to the atmosphere in the leaves. 



In the first instance it has a common use ; but finally it 

 receives a particular destination according to the kinds of 

 plants and their parts. fc 



It is only carried to the points where it is wanted, so that 

 there is no universal circulation. 



Being composed, principally, of the two general substances 

 of which mention has been made, the woody and the paren- 

 chymatous, as soon as one of these is employed in the process 

 of vegetation, it is necessary that the other should be disen- 

 gaged and deposited in the vicinity; so that the application 

 of one substance is the separation of the other. 



XIII. On the Extraction of Selenium from the Residuum of the 

 Sulphuric Acid Works of Lukawitz in Bohemia ; and on the 

 Cause of the Odour of Tellurium. By Professor Scholz, of 

 the Polytechnic Institution of Vienna* 



TN the winter of the years 1821-2, I examined the thick 

 •* matter which collects in the leaden chambers of the Auer- 

 sperg manufactory of sulphuric acid at Lukawitz in Bohemia, 

 and which, from its gray colour inclining to red, had excited 

 the attention of M. Schrattenbach, the director of the works, 

 and a very active man, who delights in the promotion of the 

 natural sciences. A few experiments upon it with chemical 

 tests immediately showed that it contained selenium, of which 

 I have now extracted from it several ounces in its purest 

 form. As this residuum was not of such a compound nature 

 as that of the Gripsholm Works, from which Berzelius first 

 extracted selenium, I was enabled to make use of a process 

 much more simple than the one he adopted to obtain that 

 body. The substance was introduced into a tubulated retort, 

 with muriatic acid and a little nitric acid ; and nitric acid being 

 added from time to time, was evaporated nearly to dryness on 

 a sandheaL. It was now repeatedly lixiviated with boiling 

 water; the solution filtered, concentrated by evaporation, and 

 mixed with a solution of sulphite of ammonia, which had been 



* From Scliwcijigcr's Journal fitr C/iemic, &c. N. R. band viii. p. 231. 

 L 2 prepared, 



