ON THE TARTRATE OF IRON AND AMMONIA. 275 
color of periodide of mercury is changed when in contact 
with gaseous ammonia to a dull white." He found .784 
grammes of periodide of mercury in an atmosphere of gaseous 
ammonia, to absorb .055 grammes of the gas, from which he 
calculates the compound to contain 1 atom periodide of mer- 
cury, and 2 atoms (" deux atomes simples ou un atome dou- 
ble") of ammonia. 
The description of this combination, as given by Rose, 
agrees very well with that above mentioned, and they are no 
doubt identical. 
The orange coloured salt, formed by the action of a limited 
portion of water upon this compound, contains less ammonia, 
and is probably composed of 1 atom HgP with 1 atom HN 3 . 
ART. L VII.— ON THE TARTRATE OF IRON AND AMMONIA. 
By William Procter, Jr. 
Several druggists of this city having been called upon for 
tartrate of iron and ammonia, which, from its novelty in a 
medical point of view, was not to be obtained, I have been in- 
duced to make some inquiry into the character of the salt, and » 
ascertain an eligible process for its preparation, in case it 
should gain favor with the medical profession. The absence 
of all notice of it, in any of the chemical works usually to be 
obtained, is the motive for entering so much in detail. 
The process for preparing the tartrate of iron and potassa, 
published in the last number of this journal, has been taken 
as a type in the formation of the succeeding formula, and the 
advantages of that process apply with equal force to the one 
under consideration. 
The first step is to form the bitartrate of ammonia, as this 
salt is not, like the analogous one of potassa, ready at hand. 
It is readily made by dissolving four equivalents of tartaric 
acid in a suitable quantity of water, and adding gradually, one 
