96 CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY. [bull. 167. 
tion of the hydroxyls as well as of the imide hydrogen atoms; in short, 
quite a number of stereoisomers may be conceived. I have thus far 
sought in vain for indications of the existence of such forms. 
Experimental Part. 
Analytical methods. — Salts of trimetaphosphimic acid and derived 
bodies are easily decomposed by fusion with sodium carbonate. As 
the process involves oxidation it is essential to keep the mass in a 
state of fusion for some time with access of air. Salts of silver of other 
easily reducible metals and those in which it is desired to determine 
alkali or nitrogen must be decomposed by strong sulphuric acid. The 
substance, contained in a platinum crucible, is lirst moistened with dilute, 
and then covered with 4 or 5 cubic centimeters strong sulphuric acid, and 
the covered crucible heated to fuming for an hour in a radiator, care being 
taken that the fumes do not escape. In determining alkali metal, the 
resulting phosphoric acid may be conveniently removed by the ferric 
chloride- acetate method. As the water of crystallization can not be 
completely expelled by heat without partial decomposition, it is best 
determined, together with the hydrogen of the salt proper, by combus- 
tion. This is conveniently carried out in a short combustion tube with 
a 10-centimeter spiral of oxidized copper gauze, the substance, contained 
in a boat, being covered with fused potassium bichromate. As nitrous 
fumes are formed in abundance, the usual precautions must be taken. 
In the following, where more than one determination is given, the 
numbers always refer to different preparations. 
Preparation of trimetaphosphimic acid. — The sodium salt affords the 
starting material for all preparations of trimetaphosi)himic acid. It 
may be obtained by saponifying triphosphonitrilic chloride by alcoholic 
soda, but with much loss, owing to the formation of ethers and other 
substances of unknown nature. The chloride, as observed by Liebig 
and by Gladstone, is practically unacted on either by water or anhy- 
drous ether, but, as I have already pointed out elsewhere, its decompo 
sition may readily be effected by shaking its ethereal solution protract- 
edly with water, whereby intimate contact is secured. Decomposition 
by ether and water alone, however, results in much loss, as the liberated 
hydrochloric acid rapidly decomposes trimetaphosphimic acid. The 
following method is perfectly satisfactory and gives practically the 
theoretical yield. 
Thirty grams of the chloride are dissolved in 150 cubic centimeters eth er 
free from alcohol, and the solution gently agitated with a solution of 110 
grams crystallized sodium acetate in 200 cubic centimeters water, the agi- 
tation being conveniently effected by slowly rotating with a small turbine. 
After about fifteen hours, well-formed crystals of sodium salt begin to ap- 
pear, and about seventy or eighty hours are required for complete decom- 
position. This point is best observed by evaporating a few drops of the 
ether and taking up the residue with water, any undecomposed chloride 
