268 Dr Turner on Lithion-Mica. 



produce the same effect, though much less distinctly. The 

 sulphate is exceedingly well adapted for the purpose, and this 

 is a very useful fact, as it enables us at once to distinguish 

 lithia from every other salifiable base with which it can be 

 confounded. The muriates of strontia and lime both occa- 

 sion a red light when they are moistened and brought into 

 contact with the flame of a candle. The acetate of lime has 

 not that property, but the acetate of strontia has. But no 

 sulphate except that of lithia possesses it. The sulphates of 

 lime and strontia, whether moist or dry, give no trace of red ; 

 and even if they did, their insolubility at once distinguishes 

 them. * Magnesia is the substance which is most likely to be 

 mistaken for lithia, and the sulphate of that base does not in 

 any way affect the flame of a candle. The sulphate of lithia, 

 on the contrary, has a distinct effect even when minute quan- 

 tities are used. Thus, to give an extreme case, I have made 

 the redness visible to several persons at a time, with less than 

 1555th of a grain of the crystallized sulphate of lithia. In 

 operating with such minute quantities, a proportional degree 

 of care is of course requisite. The best mode of performing 

 the experiment is as follows : A particle of the crystallized 

 sulphate is taken upon the point of a pen-knife, and held for 

 an instant in the flame of a candle to make it adhere to the 

 steel ; it is next moistened in water, and brought into contact 

 with the extreme border of the flame at its lower part where 

 it burns blue. A red light then appears, forming a sort of 

 fringe to the proper flame of the candle, but it disappears as 

 soon as the salt becomes dry. By moistening it again, the ef- 

 fect is renewed, and the experiment may be repeated a great 

 many times with the same particle of salt. If the sulphate is 

 held in the body of the flame, a mixture of colours is produc- 

 ed, which lessens the distinctness of the effect, and for that 

 reason I have expressly mentioned that it should barely touch 

 the outer border of the flame. It is of course necessary to 



" If the sulphate of strontia be finely pulverized, and then made very 

 moist with water, it does communicate a red colour when placed upon the 

 wick of a candle. I have not observed the same effect from sulphate of 

 lime- 



11 



