11 



2. Add 0.2 gm. quinine to 100 mils of water in a flask. Shake 

 flask. Note that only a small amount is dissolved, if any. 

 Why ? Test reaction with litmus and explain results. To 

 above mixture add 1 mil of dilute sulphuric acid. Re- 

 sults. Why? 



Use above solution for the following experiments : 



3. To 5 mils of the above solution in a test tube slowly add 

 a solution of potassium carbonate until alkaline. Results. 

 Why? Acidify with dilute sulphuric acid. Results. 

 Why? 



Explanatory : — Alkaloidal salts are feeble bases and are thrown 

 out of solution by the addition of fixed alkalies and their carbonates 

 which unite with the acid of the alkaloidal salt. The above pre- 

 cipitate was, therefore, the freed alkaloid which is insoluble in 

 water. By the addition of the acid the soluble suplhate or bisul- 

 phate was again formed. 



4. To 5 mils of solution from No. 2 add a solution of potas- 

 sium hydrate until alkaline. Add excess of distilled water, 



shake. Results. Explain. 



5. Place 5 mils of the solution from No. 2 in each of 5 test- 

 tubes and add slowly one of the following reagents to 

 each. Note the formation of a precipitate in each. Test 

 the solubility of the precipitates in an excess of water as 

 in 4, and note results. Tabulate results. 



Reagent Color of Precipitate Solubility in Water 



Tannic Acid 



Iodine in potassium iodide 



Picric acid 



Mercuric Pot. Iodide (Mayer's Reagent) 



Phosphotungstic acid 



6. To 10 mils of the solution from No. 2 add solution of po- 

 tassium hydrate until alkaline, then add 10 mils of ether, 

 shake, allow ether to rise to the top. Draw off ether and 

 save. Add a few more mils of ether and proceed as be- 

 fore. Acidify a small amount of the remaining aqueous 



