552 Mr, PoRRETT on the nature of the Salts 
consequently it belongs to the same class of acids as does the 
ferruretted chyazic acid, I shall call it henceforth the sulphu- 
retted chyazic acid, and conclude this communication with 
giving some description of its salts, with my analyses of two 
of the most important of them, and by which the composition 
of all its other salts may be known with comparatively little 
trouble. 
Sulphuretted Chyazates, 
Of potash, a deliquescent salt soluble in alcohol. 
Of soda, ditto, crystallizes in rhombs. 
Of lime, ditto, soluble in alcohol, from which it may be 
obtained as a mass of needle form crystals. 
Of ammonia, ditto, not crystallizable. 
Of magnesia, ditto, when dried has a micaceous appearance. 
Of alumina, crystallizes in octohedra which do not deliquesce. 
Of barytes, a deliquescent salt, crystallizing in long slender 
prisms of a brilliant white colour. 
Of strontia, a deliquescent salt crystallizing in long slender 
prisms in groups radiating like zeolite. 
Of oxide of silver, a white insoluble powder. 
Of protoxide of mercury, a white insoluble powder. 
Of potash and prussiate of mercury, this salt is remarkable 
for its brilliant silvery lustre, and for its very compound nature, 
as all the four principles mentioned in the name which I here 
give it, enter into its composition. It has but little solubility in 
cold water, but is very soluble in hot, from which it may be 
obtained in crystals by cooling. 
Of protoxide of copper, a white powder insoluble in w^ater 
and in most acids, decomposable by alkalies or by distillation 
