vow 
enantiotropic. According to Warrace’s determinations the transition 
point lies at 109°. As it has, however, appeared io me when I 
repeated the experiments with ammonium chloride that the value 
that Warracr gives, is considerably too low, | have determined the 
transition point of ammonium bromide in the same way as in the 
first paper. I already announced these experiments in my first paper 
in § 8, and I communicated the preliminary result that ammonium 
bromide possesses a transition point at 187° at the Natuur- en 
Geneeskundig Congres in April 1915). I have, however, been 
obliged to postpone the full description of these experiments till now. 
In 1916 there appeared two papers by Smita and EasrrackK: in 
the former?) they communicate that they discontinued the deter- 
mination of the transition point of ammonium chloride at the publi- 
cation of my first paper, but that they have continued the experi- 
ments with ammonium bromide. Their conclusion derived from 
determinations of the solubility in water is that the transition point 
lies at 187°.3. In the latter paper *) it is stated that ammonium 
iodide does not possess a transition point between — 19° and 136°. 
In what follows I will briefly give the results of my investigation 
with ammoninm bromide, whick as appears from the above mentioned 
“preliminary communication, agree with those of SMITH and BasTLACK, 
and those of ammonium iodide, which have yielded the transition 
point, which had not been found up to now. 
The resuit obtained with ammonium iodide, has already been 
published by Mr. HooGeNBoom in his Thesis for the Doctorate. *) 
15. Thermal determination of the transition point of ammonium 
bromide. 
The experiments deseribed in $$ 15 
with ammonium bromide prepared from hydrogen bromide and 
ammonia. Hydrogen bromide was obtained by leading purified bro- - 
mine (method Megrum Terwoert) *) with hydrogen over heated platinum ; 
ammonia was obtained by fractionating liquid ammonia obtained 
18 have been carried out 
from ammonia liquida and leading it into water. 
When we try to determine the transition point of ammoninm 
bromide in the well-known way through curves of heating and 
cooling, it appears that the conversion of the two modifications into 
1) Handelingen van het 15e Ned. Nat. en Gen. Congr. (April 1915) p. 242 e.seq. 
2) Journ. Amer. Chem. Soc. 38, 1261, (1916). 
3) Journ. Amer. Chem. Soc. 38, 1500, (1916). 
4) Dissertatie Amsterdam (July 1916), p. 64 and 65. 
5) Dissertatie Amsterdam (Nov. 1904), p. 6 et seq. 
Proceedings Royal Acad Amsterdam. Vol. XIX. 
