120 
.RESULTS OF PHYSICAL AND CHEMICAL INVESTIGATIONS. 
some time since. We will suppose a case which very frequently occurs, as in the analysis 
of waters for instance A liquid containing a mixture of lime, magnesia, and the alkalies 
to he separated. Solution of sal-ammoniac, excess of ammonia, and oxalate of ammonia 
are added to precipitate the lime, which is then filtered off. To the filtrate is added 
phosphate of ammonia or solution of tribasic phosphoric acid (keeping excess of ammonia 
in the solution), by which the phosphate of magnesia and ammonia is precipitated. This 
is separated with the usual precautions, and the clear liquid evaporated to dryness, and 
the residue heated to drive off ammoniacal salt. Usually also the excess of phosphoric 
acid will expel all the hydrochloric acid at the same time. To be perfectly safe, how¬ 
ever, the residue is treated two or three times with nitric acid and calcined, by which the 
whole of the hydrochloric acid is removed, and there remains nothing but phosphoric 
acid, potash, and soda. This residue is then treated in a flask with a large excess of 
granulated tin and with nitric acid. In the reaction which occurs, the stannic acid 
formed combines with the whole of the phosphoric acid, forming a compound perfectly 
insoluble in water and in nitric acid. The mass is diluted and filtered ; the filtrate con¬ 
taining only the nitrates of the alkalies may be evaporated to dryness and calcined to 
form carbonates, or treated with hydrochloric or sulphuric acid to form chlorides or sul¬ 
phates which can be weighed. The relative quantities of potash and soda may then be 
determined either by the indirect means, or directly by chloride of platinum. 
The only source of error in working this process is the presence of hydrochloric acid 
in the residue when treated with tin and nitric acid: this is readily avoided in the 
manner described. 
The Action of Iodine on Ammonia. —The explosive body produced by the 
action of aqueous ammonia upon iodine, sometimes called “ iodide of nitrogen ,” has 
been investigated by several distinguished chemists with the view of determining its com¬ 
position and constitution. It has resulted that several different formulae have been 
given; and it has become evident that by modifying the conditions under which the 
iodine and ammonia are brought together, the composition, and to some extent the pro¬ 
perties, of the resulting compound may be changed. 
Thus Bineau assigned to the product the formula NHL,, regarding it as an ammonia 
in which two equivalents of hydrogen were replaced by two equivalents of iodine. 
Bunsen, by the action of ammonia upon an alcoholic solution of iodine, obtained a body 
to which he gave the formula 
nh 3 ni 3 . 
This compound may be viewed as an ammonia in which one atom of hydrogen has 
been replaced by an ammonium having 3 of iodine in the place of 3 of hydrogen; 
thus:— 
N 
fH 
II 
L(NHI 3 ). 
Dr. Gladstone, however, obtained by the same means a body having the composition 
assigned by Bineau to his compound. By the action of dry ammonia upon iodine, a 
body is obtained to w r hich Millon gives the formula N H 3 1, and to which Bineau assigns 
the composition 
3 (NH 3 )Io. 
It will be seen that all the compounds yet obtained contain hydrogen, and are ob¬ 
viously substitution-products of ammonia. The name “iodide of nitrogen ” is therefore 
inaccurate, and can no longer be properly used to designate these bodies. 
Dr. F. Guthrie, the Professor of Chemistry in the Boyal College of Mauritius, has 
recently discovered a new compound of this class, and one which in several respects is 
very remarkable. 
This new body has the composition 
nh 3 l 
and must be regarded as the iodide of an ammonium in w r hich one of the liydrogeu atoms 
is replaced by an iodine atom. Thus :— 
