lately discovered hi Plailna. $1 



both eminently fugitive. In regard to green, we can sup^ 

 pose it to be easily produced wherever a yellow and a blue 

 can exist; the inference is therefore but natural for any 

 mixture of these to centre in the former. The comparison 

 will, I am fully persuaded, lose nothing of its value by ex- 

 tending it ; we may therefore, for the present, further as- 

 sume the following positions : 



1st, That both the new metal and tungsten are difficultly 

 soluble in acids. 



2d, That the oxide of one as well as the other is soluble 

 in alkalies. 



3d. The new metal, when fused with potash, forms a 

 green mass. 



4th. That tungsten may perhaps give the same result, 

 since wolfram, one of its ores, gives a green scoria when 

 fluxed with potash. 



5th. Neither of the metals gives colour when fluxed with 

 borax. 



6th. That the blue colour in both metals is soluble in 

 water, and may be easily changed or dissipated by heat. 



The fugacious nature of the blue tint, so peculiar to both 

 these metals, is often very perceptible in tungsten; and 

 this distinctive mark may be exemplified in many instances. 

 I have observed paper in which some oxide had been iil- 

 tered, when exposed to the sun become of an elegant blue 

 colour; and the same paper during tfoe night or in the dark 

 lost its colour, and regained it on exposure to the sun. 

 Whether it be the heat or light of tjie sun, or both, that 

 produces the change, remains to be examined. 



In the following experiment it appears that heat is the 

 cause of dissipating the blue when in solution. 



• If a cylinder of zinc be left for some time in a solution 

 of the triple acidulous salt, generally called tungstic acid, 

 the liquid will soon become of a most brilliant blue ; espe- 

 cially if the zinc be frequently moved, as if to stir the fluid. 

 When the zinc has produced a full effect it may be with- 

 drawn, and the solution then placed over the flame of a 

 lamp, or in a gentle heat, to evaporate. In a short time 

 the colour will lessen in its intensity, and at length totally 

 vanish, leaving the remaining solution nearly colourless. 

 This is not the only instance of the fleeting nature of the 

 blue colour of tungsten, though a very effectual one to 

 elucidate this singular peculiarity. 



That zinc and iron turn some preparations of tungsten 

 blue, has already been noticed by several authors ; I do not, 

 however, recollect that the entire dissipation of the colour 



bv 



