In this way
every possibility of loss is excluded, and yet a very careful washing
provided. Then when, after being emptied by the siphon, the apparatus
fills again, every particle of the emulsion which might have formerly
been pressed down into the interstices of the sieve would now be driven
up again by the upward pressure of the water entering from below, and
thus the sieve would always be kept clear and open.
[Illustration: FIG. 3.]
The great advantages of this apparatus are as follows: 1. From the
moment the lid is closed one can work by daylight. 2. The method of
washing in moving water is combined with that of complete change of
water. 3. The emulsion never comes in contact with metal. 4. Whoever
wishes to prepare dry gelatine only requires, when the washing is over
and the vessel perfectly emptied, to leave the emulsion to drip for a
time, and then to lift out the sieve and its contents and place it in
a suitable vessel with absolute alcohol. The latter should be changed
once, and when sufficient water has been extracted the sieve should be
withdrawn from the vessel and the emulsion allowed to dry spontaneously.
In this way all trouble occasioned by changing from vessel to vessel is
avoided, and there is no loss of material.
This apparatus is principally valuable in dealing with large quantities,
since it saves a great deal of labor, and affords perfect certainty of
the emulsion being well washed.
Pages:
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98