294 M. Mitscheriich on a tvew Jcid of Selenium. 



Before concluding these observations, it may be expected 

 that I should attempt to answer a question which every per- 

 son must have put to himself. Whence comes the silex which 

 circulates so abundantly in the juices of the bamboo ? If we 

 consult on this subject our best systematic writers on chemis- 

 try and botany, we shall find it ranked as a " foreign ingre- 

 dient,'" an intruding element which the plant had derived from 

 the pecuhar soil in which it vegetated. Those who examined 

 the drawings and descriptions of the distribution of silex in 

 the Equisetum hiemale, which I submitted to the Society 

 some years ago, will concur with me in the opposite opinion, 

 that the silex is an integral portion of the plant itself, and pro- 

 bably performs some important function in the processes of ve- 

 getable life. 



Art. X. — Oil a new Acid of Selenium.* By M. E. Mit- 

 scHERLTCH, Profcssor of Chemistry in the University of Ber- 

 lin, F. R. S. Ed. &c. &c. I 



The existence of this very interesting compound, which we 

 noticed briefly in a former number of this Journal, was origi- 

 nally observed by M. Nitzsch, who has long assisted M. Mit- 

 scheriich both in preparing for his lectures and in conducting 

 his researches. M. Nitzsch, in order to prepare a seleniate of 

 potash, decomposed the seleniuret of lead by fusion with nitre, 

 dissolved the resulting seleniate of potash in water, evaporated 

 the solution to dryness, and heated the residue with sal-ammo- 

 niac. As it was necessary to employ an excess of nitre, he en- 

 deavoured to separate that salt from the seleniate of potash by 

 crystallization. After the separation of the greater part of the 

 nitre, he obtained crystals which had the following characters. 

 They had the form of sulphate of potash, and were analogous 

 to that salt in relation to polarized light. They formed a 

 neutral solution with water, were free from water of crystal- 

 lization, deflagrated like nitre with red-hot charcoal, yielded 

 an insoluble precipitate with the salts of baryta, gave rise to 

 an evolution of chlorine when boiled with muriatic acid, and 

 underwent no change by the action of sulphurous acid. After 



* Abstract from the Annates de Chimie ei de Physique, xxxv. 100. 



