Intelligence and Miscellaneous Articles. 225 



employed one-half the quantity of nitrate of potash, or what 

 I am inclined to think superior, nitrate of soda, employed to 

 prepare the amethystine salt, and exposed the mixture to a 

 somewhat higher temperature. I have never obtained it un- 

 mixed with the purple salt, but owing to its being a much 

 more stable compound than that is, it remains for a consider- 

 able length of time undecomposed at ordinary and even elevated 

 temperatures, if excluded from the air. This furnishes an easy 

 method to prove the green salt free from the amethystine salt. 

 Its properties appear analogous to those of the amethystine 

 salts, except with respect to its permanency; acids liberate 

 oxygen, changing the solution to pink, which gradually disap- 

 pears ; chlorine rapidly converts it into the pink salt. It is 

 capable of filtration without being entirely decomposed, but 

 long contact with organic matters appears to resolve it into 

 oxygen and sesquioxide of iron. I regret that at present I 

 have not been able to obtain this green acid of iron in such a 

 state of combination that I can accurately determine its posi- 

 tion, but I hope during the next session of the Chemical So- 

 ciety to lay before its members a more detailed investigation 

 of the pink chlorinated compound, and also of the green oxide, 

 and to ascertain their composition and properties. 

 Romford. 



XXIX. Intelligence and Miscellaneous Articles. 



EXPERIMENTS AND OBSERVATIONS ON MOSER's DISCOVERY. 

 BY MESSRS. PRATER AND HUNT. 



IN the Athenseum, No. 812 (1843, p. 485), appears a paper on 

 this subject by Mr. H. Prater, in which he proposes " to demon- 

 strate, that the radiation discovered by Moser is not invisible light, 

 as he supposes, nor heat, as has since been supposed." In this 

 paper he relates experiments with regard to the nature of the sub- 

 stances that produce spectra, to the effect of dissimilar metals, the 

 eiFect of unequal heat on the plates and coins employed, and the 

 effect of heat generally ; also as regards the distance from the plate 

 at which images may be taken, as regards impressions on glass, as to 

 polished surfaces not appearing capable of receiving the impressions ; 

 as regards comparative polish in metals, to solve the question which 

 metal receives fastest, copper or silver ? ; as regards the effect of in- 

 terposed substances, on the influence of mass, and as to the question, 

 does the thinness of the plate exert an influence ? 



" Every substance I have tried," says Mr. Prater, " has produced 

 its spectrum when left on a polished copper plate ; — coins, whether 

 of gold, silver, or copper, platinum, nickel, brass, pieces of glass, 

 wafers (red, blue and white), peppermint or rose drops, whalebone, 

 talc, gum, a horse-hair ring, lava from Vesuvius, Indian-rubber (but 

 slight), and sealing wax." His experiments give him reason to con- 



Phil. Mag. S. 3. Vol. 23. No. 151. Sept. 1843. Q 



