204 S. P. Sadtler on Fischer's Salt. 
Again, Gauhe will find that Gibbs and Genth never even men- 
tioned the use of (NH,),€0, in this connection, so that his ex- 
periments were plainly made under different conditions from 
those proposed. 
2d. Determination of €o. I prefer to determine €o as neutral 
ve 
into sulphate with the aid of aqua regia and sulphuric acid. The 
results are good, although not so exact as in the case of the fusi- 
ble double sulphates. I also determined €o as metal by H after 
its precipitation — oxyd by Cl and acetate of soda, 
. me 
is therefore referred to the original paper. Suffice it to say, that 
_ for nitrates and nitrites to which it is applicable, it is an excel- 
lent method. The loss of the combustion-tube can be nothing 
but N and H,®. If, therefore, the €aCl, tube retains the H:,? 
- * Ann. Ch. uw. Ph., 131, 363. + Ann. Ch. u. Ph., 72, 40. 
Se nh Revi Boe. Jour. Ch, Soe., 1868, p. 90. 
