286 APPLICATION OF PLATINA ON PORCELAIN. 



be added immediately, to ("ufpend the ebullition, and prevent 

 the matter from being redifiblved, and becoming a mere folu- 

 tionof filver. The white precipitate is then to be collected 

 on a paper filter, and dried. 

 Its weight more This precipitate is fulminating filver, and amounts to more 

 It Tetonates'"'* ^^'*" ^^'^ ^^*^ weight of the lunar cauftic employed. The de- 

 more ftrongly tonating power of this preparation greatly exceeds that of ful- 



than fulmi- minating mercury, prepared in Howard's or my way, even in 



nating mercury, , r n • t i • ^ 



being touched much Imalier quantity. It detonates in a tremendous inanner> 



with a glafs on being fcarcely touched with a tube of glafs, the extremity 

 fulphuric acid' ^^ which has been dipped in concentrated fulphuric^cid (oxi- 

 fulfurique), even in that of the (liops. One grain of this ful- 

 minating filver, placed on a lighted coal, gave fuch a loud re- 

 placed tfn a port, that it deafened the ears of the perfons prefent. The 

 lighted coal, ^^^^ thing happ«ns on placing a little of the fame preparation 

 fpark drawn on an eledric pile, with the interpofition of a bit of paper, and 



through It from drawing a fpark from its centre by means of a flip of metal, 

 the eledlric pile. far . . . ^ ^ 



The paper will be either pierced or torn. 



IX. 



Of the Application of Platina or Porcelain. % KLApROTH.f 



Platina never JlLATINA, as far as I know, has never yet been employed 

 yetapphed on -^^ encauftic painting. Accordingly I thought it not amifs, to 



make fome experiments on the fubjecl, the refult of which 



did not deceive my expectations. 

 Gold and filver Gold and filver are the only metals, that have hitherto been 

 ufed itrthis"way ^nap^oy^d in the metallic form in painting or ornamenting por- 

 in the metallic celain, glafs, or enamel. Gold anfvvers this purpofe fo com- 

 a r* Id f pletely, that it leaves nothing to be defired : but filver is far 

 completely, from affording equal fatisfaclion. As it is of lefs denfity than 

 but filver does 

 not cover the 



gold, it cannot be ufed fo thin, and does not cover the porce- 

 groundfo well, lain Of Other fubftance fo well. Another reafon why it is lefs 

 and is liable to applicable to the purpofe of painting on porcelain is its property 

 of having its metallic luftre tarnifhed by fulphurous emanations, 

 all kinds of which blacken it. This unfavourable circura- 

 flance prevents filver from being employed in fine enamel 

 painting, and confines the ufo of the metallic fubftances in that 

 only to gold. 



* Abridged from Scherer's Journal der Chimie^ 1802. No. 4. p. 4 13. 

 5 . Platina 



