Bauhaus-Universität Weimar

Handbook for the Physiological Laboratory. Text
Burdon-Sanderson, John Scott E. Klein Michael Foster T. Lauder Brunton
broken up with a glass stirring rod ; this may be done much 
more easily if the rod is very thick or has a bulbous end. 
If simple agitation or heat suffices to dissolve a substance, it 
may be placed in a test-tube, but if it requires stirring it should 
be put in a test-glass (as the rod is apt to break the tube), and 
afterwards transferred to a tube if heat is to be applied. 
The fact of a substance being soluble in a liquid is ascertained 
by the quantity which was at first put in becoming gradually 
less, and finally disappearing. When it is only sparingly soluble 
no diminution in the substance may be observable, and the 
liquid is then to be decanted or filtered off, and something 
added or done to it which will indicate the presence of 
the substance, if any has become dissolved. It is some¬ 
times more convenient, especially when alcohol and ether are 
employed as solvents, to evaporate the filtered liquid to dryness, 
and see whether it leaves any residue or not. 
Pul verize a little albumin in a Wedgwood mortar. Put a little 
of it in several test-tubes, and test its solubility in the following 
reagents :— 
fl. Water : The albumin will dissolve, and may be shown to 
be present in solution by boiling, when it will be precipitated. 
f2. Liquor Potassæ : The albumin will dissolve, and may be 
precipitated from the solution by neutralizing. 
3. Alcohol. 
4. Ether : The albumin does not dissolve either in alcohol or 
ether. The clear liquid, when filtered and evaporated, will leave 
no residue. 
+5. Acetic Acid dissolves albumin. On adding potassium 
ferrocvanide to the solution, a precipitate falls. 
+6. Concentrated Hvdrochloric Acid : The albumin dissolves, 
and the solution gradually becomes blue, then violet, and, 
lastly, brown. Test this with one portion at the temperature of 
the room, and with another heated over a spirit-lamp. The 
same changes will occur in both, but much more quickly in that 
which is heated. A precipitate falls when either solution is 
7. Concentrated Sulphuric Acid : The albumin dissolves, and 
more quickly if heated. 
+8. Concentrated Nitric Acid: The albumin dissolves, form¬ 
ing a yellowish solution. When boiled it dissolves more quickly. 
YV hen the solution is allowed to cool, and ammonia added to 
it, it becomes orange-coloured. 
8. Coagulation of Albumin.—One of the most remark¬ 
able properties of albumin is its precipitation from neutral solutions 
as an insoluble coagulum by boiling.


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