410 Intelligence and Miscellaneous Articles. 



every trace of acid ; but when the acid from the white infusible 

 chloride, after I had separated it as well as possible from the yellow 

 one, was again mixed with charcoal and treated with chlorine, I 

 constantly obtained yellow and white chloride ; less, it is true, of the 

 first than when the mixture of the two acids as they occur in the 

 mineral was employed ; but even when the operation was very fre- 

 quently repeated with the acid from the white chloride, it was not 

 possible to obtain by this method a pure white chloride free from 

 yellow. I observed however that the white chloride was only par- 

 tially sublimed. When it was separated as much as possible from 

 the yellow chloride, and by sublimation also from a white non-vola- 

 tile residue, it at last afforded an acid, which on treatment with 

 charcoal and chlorine yielded a tolerably pure, white, wholly vola- 

 tile chloride, the chloride of niobium. The white fixed residue 

 yielded with charcoal and chlorine a large quantity of yellow chlo- 

 ride ; and after removing this by sublimation, again left a white non- 

 volatile residue, which, on being again subjected to a similar treat- 

 ment, afforded the same products. 



On comparing this behaviour of the yellow chloride with that 

 observed on treating a mixture of pure tantalic acid and charcoal 

 with chlorine, I obtained a perfectly similar yellow chloride and a 

 white non-volatile residue ; but the quantity was far smaller, and its 

 production could be entirely avoided if, in the preparation of the 

 chloride of tantalium, every trace of humidity and atmospheric air 

 had been carefully excluded. Moreover, the sublimed yellow chlo- 

 ride from the Bavarian mineral very much resembled the chloride 

 of tantalium. This similarity likewise extended to the acids pre- 

 pared from the two chlorides ; they behaved so much alike, that it 

 was only after long-continued investigation properties were disco- 

 vered by which they might be separated. 



Both in the preparation of chloride of tantalium with the tantalic 

 acid from the Finland tantalite, but especially in that of the yellow 

 chloride from the Bavarian mineral, I frequently obtained consider- 

 able quantities of a red chloride, which was still more volatile than 

 the yellow one, and proved on examination to be chloride of tung- 

 sten. When the chlorides are exposed for some time to the air, the 

 tungsten can be removed by digestion with ammonia as readily 

 soluble tungstate of ammonia. 



Sometimes chloride of tin and chloride of titanium were obtained 

 in preparing the chloride; they could be readily distinguished, by 

 their fluid state of aggregation, from the other chlorides. 



The formation of the chlorides of tungsten and tin was in so far 

 remarkable, as the acids from which the chlorides were prepared 

 had been kept in a moist condition for a long time in contact with 

 sulphuret of ammonium. I draw especial attention to this circum- 

 stance, because, unless perfectly freed from these impurities, the 

 chlorides and the acids prepared from them are obtained with very 

 different properties. 



The yellow chloride from the Bavarian mineral differs therefore 

 principally from the chloride of tantalium by its leaving a white 



