534 
Mr. PoRRETT on the nature of the Salts 
per-oxide of iron by its combustion, which will be related pre- 
sently, contain 6 .y 6 grains of black oxide of iron and 11.71 
grains of red oxide of iron, but as the whole of the iron in the 
ferruretted chyazate of potash is in the state of black oxide, 
these 11.71 grains of red oxide must be reckoned as 10.5 
grains of black oxide, which added to the 6.76 grains gives 
17.26 as the quantity of black oxide of iron contained in 100 
grains of the ferruretted chyazate of potash. 
C. 100 grains of crystallized ferruretted chyazate of potash 
dissolved in water and poured into a solution of green sul- 
phate' of iron gave a precipitate which, treated exactly as the 
last, was ferruretted chyazate of per-oxide of iron and weighed 
89.3 grains, the elements of the Prussic acid contained in which 
weigh 30.4 grains, as may be seen in the analysis before re- 
ferred to. 
D. 100 grains of the same crystallized salt, decomposed 
by sulphuric acid, gave a quantity of sulphate of potash which, 
after fusion in a platinum crucible by a strong red heat, weighed 
7^*5 gi'ains : now as 100 grains of sulphate of potash in this 
state contain, according to Dr. Thomson (Annals of Philosophy 
for Oct. 1813), 50.1 grains of potash, therefore these 78.5 
grains must have contained 39.33 of that alkali. 
Hence, neglecting minute fractions, the crystallized ferru- 
retted chyazate of potash is composed of 
Grains. Water A - 
17.26 black oxide of iron B 
30.40 elements of Prussic acid C 
Potash D 
13.0c 
ferruretted chyazic 
acid 
- 39 - 3 ' 
47 . 6 ( 
100.00 
