36 Mr. W. Crowder on the Fatty Acid of Cocculus indicus. 



100-00 10000 351-55 



These numbers con-espond closely with the theoretical result, 

 leading to the formula C^^Hs^OS + BaO. 



Bassiate of Silver. — I next attempted the preparation of a 

 silver salt, and after three or four trials, found that the best 

 method of preparing it free from excess of acid was to make an 

 exceedingly dilute solution of soda in alcohol, and also an ex- 

 ceedingly dilute solution of nitrate of silver in the same men- 

 struum. 



The proportions used were about 20 grains of soda salt dis- 

 solved in 5 or 6 ounces of rectified spii'it, and about 12 or 13 

 grains of fused nitrate of silver also dissolved in the same quan- 

 tity of alcohol. The solution of soda salt was added to the solu- 

 tion of nitrate of silver in small successive quantities with vigor- 

 ous stirring in the intervals, and the mixtm-e was made in the 

 cold ; since I found that, by mixing them together hot, more or 

 less decomposition invariably took place. The white curdy pre- 

 cipitate is allowed to subside in the dark, the supernatant liquid 

 is drawn off, and the precipitate filtered in the dark, as the salt 

 blackens by exposure to the light when alcohol is present. It 

 was then washed mth alcohol till free from excess of silver, dried 

 first in vacuo and then at 212*^. 



Thus prepared, it is a light white powdei-, without any appear- 

 ance of crystallization ; it is highly electrical, insoluble in water, 

 alcohol, and in aether. It speedily blackens in contact with 

 alcohol, but when freed from that liquid it undergoes decompo- 

 sition much more slowly. 



The following are the results of analysis : — 



I. 6-258 grains of silver salt, prepared as above detailed, gave, 

 on ignition, 1-733 silver = 27-69. 6-825 grains of silver salt, of 

 the same preparation, gave 1-875 silver = 27-46. — Mean 27-57. 



II. 6515 grains of silver salt, prepared with aqueous solu- 

 tions, gave 1-825 silver = 28-01 per cent. 5-66 grains of silver 

 salt, of the same preparation, gave 1-58 silver = 27-91 percent. 

 —Mean 27-96. 



III. [a) 4'93 grains of silver salt, prepared as No. I., gave 

 1-35 silver = 27-38 per cent, [b) 4-922 grains of silver salt, of 

 the same preparation, gave 1-346 silver = 27*34 percent.' — Mean 

 27-36. 



