430 J. (!. Dinwiddis — Hydrofluoric and FluosiUcic Acids. 



In the water titration : 



(a) NaHF, + Na,SiF, + oNaOIT = 8NaF + Si(OH) 4 + 11,0 



and in the alcoholic titrations : 



(ft) NaHF a + Na.SiF, 4- 2KC1 + NaOH = 2NaF + K s SiF, 



+ NaCl 



and the ferric chloride titration for total fluorine : 



(c) 3(8NaF) + 4FeCI, = 4(3NaF-FeF 3 ) + 12NaCl. 



If there were no complications, it is easily seen that the alkali 

 used in equation (b) would be equivalent to the sodiiirn 

 hydrogen fluoride present, while that used in (a) less that used 

 in (b) would be a measure of the sodium fluosilicate present. 



However, as has been shown by Katz* and also in the 

 present paper, when a mixture of free hydrofluoric acid and of 

 fluosilicic acid or sodium fluosilicate is titrated in alcoholic 

 potassium chloride solution, a marked absorption of free acid 

 takes place. On this account the titration as in (b) can not be 

 a measure of all the sodium hydrogen fluoride present in such 

 a mixture as that described by Greef. 



*Katz, Chemiker Zeitung, xxviii, 356, 387, 1904. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Occurrence of Germanium in Zinc Materials. — The 

 presence of small quantities of the very rare metal germanium in 

 zinc ores has been observed spectroscopically in several instances, 

 but in most cases the amounts present were too small to serve as 

 practical sources of the element. G. H. Buchanan, of the New 

 Jersey Zinc Company, has announced that in some material at his 

 disposal germanium was found in sufficient quantity to be readily 

 detected by the ordinary chemical reagents. The material is a 

 by-product from a Wisconsin blende, but its exact nature is not 

 disclosed at present. The presence of an unusual element had 

 been indicated in the course of analysis, and it was found to give 

 in acid solutions a sulphide soluble in ammonium sulphide. Then 

 several portions of one hundred grams each of the material were 

 treated with concentrated hydrochloric acid and the resulting 

 solutions were distilled to about one-half volume in the presence 

 of a current of chlorine to keep the arsenic in the pentavalent 

 state. The distillate contained the unusual element. Upon 



