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express the entire phenomenon with a certain amount of accuracy. 
As already stated, more correct results can only be obtained by 
repeating the experiments with larger quantities of hydrazine *). 
Our experiments have led to the interesting result that hydrazine- 
hydrate does not at all represent a chemical compound N,H,.H,O with 
a constant boilingpoint of about 120°, as hitherto believed. This 
however is not surprising, particularly after Kxrerscn’s experiments 
on the system sulphurtrioxide + water’). The tendeney of SO, 
and H,O to enter into combination is greater than that of N, H, 
and H,O. As the boilingpoint curve of the system sulphurtrioxide 
+ water shows a maximum not belonging to the compound H, SO, 
but to a mixture of 98,5°/, of H, SO, and 1,5°/, of H,O, it is not 
at all surprising that in the system hydrazine + water the maximum 
does not correspond with the composition N,H,. H,O. It is seen 
from these figures that a liquid boiling at 119°.8 and having the 
composition 50 mols. N,H, + 50 mols. of H,O yields a vapour 
containing about 42 mols. of N, H, and 58 mols. of water, while 
a vapour of about the composition N, H,.H,O is given off at 120°.4 
by a liquid containing about 54 mols. of N,H, and 46 mols. of water. 
From the course of the curve it appears that a maximum boiling- 
point of about 120°.5 corresponds with a liquid with about 58 mols. 
of N,H,. The experiment has shown that a mixture of about 58.5 
mols. of N,H, and 41.5 mols. of H,O has a constant boilingpoint 
of 120°.1 at 760 mm. In the table 120°.5 therefore corresponds 
with 771 m.m. 
The course of the first half of the curve plainly shows the pheno- 
menon observed by Curtius namely, that on boiling dilute solutions 
of hydrazine the distillate consists at first almost exclusively of water, 
although the boilingpoint has very sensibly increased. It may be 
assumed that the same thing happens in the reverse case of much 
hydrazine and little water; for reasons stated we have not been able 
to ascertain this. 
One of us (Dito) is already engaged with the determination of the 
viscosity of the system: hydrazine + water; while with the co-operation 
of Professor Ernst Conen experiments have already been started, 
several months ago, on the electrolytic conductivity of the same 
system and of solutions of salts in hydrazine *). 
1) Ber. 34. 4088 (1901). 
2) Curtivs states that concentrated solutions of hydrazine attack glass when 
boiling at ordinary pressure. We did not notice any such action of even highly 
concentrated solutions on our glass fractional distilling apparatus and condensing tube. 
3) Recueil 15, 179, 
