APPENDIX III. 179 



these salts again pass out and cease to be detectable 

 in the different parts of the body. 



I shall divide this paper into five sections : 



1. On the method of analysis, and its delicacy. 



2. Experiments on animals to which salts of 

 lithium were given, upon the rate of their passage 

 into the textures. 



3. On the rate of the passage of lithia-salts out of 

 the textures. 



4. On experiments on healthy persons, and on 

 cases of cataract. 



5. On the presence of lithium in liquid and 

 solid food. 



1. On the Method of Analysis, and its Delicacy. 



Three methods of preparing the substance to be 

 analyzed were followed, according as much or little 

 lithia was present. 



When plenty of lithia was present, it was im- 

 mediately detected in the spectrum by simply touch- 

 ing the substance containing lithia with a red-hot 

 platinum wire. In the case of liquids, a portion of 

 a drop was taken up on the end of the wire, and it 

 was then put into the gas-flame. 



If no lithia was thus detectable, a larger or 

 smaller portion of the substance was extracted by 

 distilled water twice or thrice, and the liquid was 

 evaporated to dryness, and the residue was then 

 tested. 



If very little lithia was present, it was necessary 

 to incinerate a larger or smaller portion of the 



