POTASSIUM NITROSOSULPHATE. 95 



any substantial analogy will be established between them. It is true 

 that both classes of compounds are metallic salts formed from nitric 

 oxide, but then, as Traube has already shown, one of the nitrogens 

 is united to the alkyl radical of the isonitramuie, whereas as we 

 have just pointed out, what little evidence there is shows that 

 one of the atoms of oxygen, and not of nitrogen, is directly united 

 to the sulphuryl of the nitrososulphate. Again, in the formation of 

 nitrososulphates, nitric oxide simply combines with a salt, while in 

 that of isonitramines it unites a salt with more metal. In the forma- 

 tion of nitrososulphates the presence of alkali, essential in the case of 

 isonitramines, may be dispensed with, as was even recognised by 

 Pelouze as regards the ammonium salt, and as has been more conclu- 

 sively ascertained by ns in the case of the potassium salt. 



