Johnson and Chittenden—New Acid Ammonium Sulphates. 188 
tain proportion of bisulphate in order to bring down the 
nitrogen below twelve and also some pyrosulphate to reduce 
the oxygen below thirty-two. 
Calculation shows, in fact, that the substance is a mixture 
of nearly one molecule of pyrosulphate (NH,),S,0,, one 
molecule of sulphate, (NH,),SO,, and three molecules of bi- 
sulphate 3(NH,HSO,). Such a mixture would have the fol- 
lowing empirical expression: S,0,,N, H,, and its centesimal 
composition compares closely with our analyses. 
Calculated. Found. 
i; 
6S 27°86 28°01 27°76 
230 53°41 53°49 
IN 14°22 14°01 14°08 
31H 4°50 67 
99°99 100°00 
Our examination of the so-called “ biammonium tetrahydrogen 
sulphate” obtained by subjecting ammonium sulphate to near 
incipient redness demonstrates that it also is a mixture. Th 
facts given by Professor Schweitzer agree substantially with 
those observed by us. 
e found in the residue after two successive heatings 
54 and 
zer's formule, but indicate that the substance is very 
nearly a mixture of two molecules of ammonium bisulphate 
(NH,)HSO, with one molecule of pyrosulphate (NH,),5,0,. 
Such a mixture is represented empirically by S,0,,N,H,,. 
The percentages required by it and those found in our analyses 
are subjoined. 
Found. 
Calculated. ome = 2. 3. 
48 28°96 29°05 29°01 28°81 
150 54°29 53°85 53°78 
4N 12°67 12°94 12°94 12-96 
8H 4°07 4°16 4° 
On adding a little aleohol (98 ad cent) and agitating, oily- 
appearing drops separated, whic 
