1865.] into and out of the Vascular and Non-vascular Textures. 401 



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 immediately detected in the 

 spectrum by simply touching 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 sub- 

 stance 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 substance, and to treat the ash with sulphuric 

 acid, to exhaust the resulting sulphates with absolute alcohol and evapo- 

 rate the alcohol extract to dryness, and to test the residue for lithia. 



Kirchhoff and Bunsen state that less than 1,000.000 ^ a milligramme of 

 carbonate of lithia = to about 8 ,ooo.ooo f a g ram can De detected by the 

 spectrum analysis. 



To determine the delicacy of the test for the chloride of lithium, the 

 following experiment was made : One grain of chloride of lithium was 

 dissolved in one litre of water. Of this solution 100 cub. centims. were 

 taken and again diluted to one litre, this latter solution containing O'l 

 grain of chloride of lithium to the litre. 



When further diluted to five times its bulk, the lithium reaction was still 

 seen faintly on a wire taking up 0'06 grain of solution. The line is most 

 distinctly visible in the evening, in a somewhat dark room. 



This dilution is equal to O'l grain of chloride of lithium in 5 litres of 

 water, or 1 grain in 50 litres. 1 litre= 15,440 grains, or 50 litres = 

 7/2,000 grains. In O'OG grain of this solution there are therefore 

 O'OOOOOOOS grain chloride of lithium, or about T^oTo^ToTo 1 ^ f a g ram of 

 chloride of lithium. This contains only ^ part of lithium, so that the 

 72 00*6 Tooth f a g ram f metallic lithium, when pure, gives the spec- 

 trum reaction. 



When the chloride of lithium was dissolved in urine, the test was from 

 twice to six times less delicate than in distilled water. 



