186 
TABLE 2. 
Duration of 
‘on « | Cl’ degree in 9% after drying 
extraction in | 
Boe at 100°. 
0 0.59 
4 | 0.36 
8 0.35 
16 | 0.34 
48 | 0.30 
products were still nitritic. Yet I performed with the gelatinous zinc- 
hydroxide some measurements concerning the solubility in NaOH, 
not because the values determined can have an absolute significance, 
but exclusively with the purpose to investigate whether this hydroxide 
reveals a higher solubility than ZnO, and consequently must be 
considered as metastable towards the latter. This proves indeed to 
be so, as the subjoined numbers demonstrate; the points found le 
considerably above the curve of solubility (AB) of ZnO. At the 
same time it appears that the solubility decreases in proportion as 
the hydroxide is kept for a longer time. This too is in favour of 
the statement, that these products must be considered as metastable 
phases inclining to stabilisation to ZnO. 
TABLE 3. 
| ition of the solution. 
Time, given in hours, since the. Composition of the solution 
reparation of the hydroxide. 
one 4 % ZnO 0/, Na,O 
eae | 10.5 11.3 
| 
sy | 9.3 11.4 
| 8.2 11.3 
Le 7.0 11.3 
: | 
For the solubility of ZnO with a Na,O concentration of 11,3 °/, we 
find by interpolation 2,3 °/,, hence considerably lower. 
Crystallized zinc hydroxide. 
It may be concluded from the above that we must consider the 
amorphous, gelatinous hydroxides as phases of varying water-percen- 
tage, they besides being extremely difficult to purify. There now 
