ANALYSIS OF FLUOR-SPAR* 



9 



made to -contain 27 per cent, of water, a propor- 

 tion very inconsistent with the properties of na- 

 tive fluate of lime, which, when strongly heated in 

 a wind furnace, loses at an average, only ^-3-5-th 

 part of its weight. The obvious inaccuracy of 

 the analysis given by the authors just mentioned, 

 induced me to make a set of experiments on it last 

 summer (1807). I selected the purest transparent 

 colourless crystal, which I found by repeated trials 

 to be very nearly pure fluate of lime. When re- 

 duced to a fine powder, and digested in nitric 

 acid, I found in the acid only a little lime, owing 

 doubtless to the partial decomposition of the fluate, 

 and minute traces of iron and lead : these two 

 metals I detected, by evaporating the nitric solu- 

 tion to dryness, heating it to redness, and then 

 dissolving the residue in muriatic acid. The co- 

 lour of the solution shewed the presence of iron, 

 and a few needleform crystals of muriate of lead 

 were deposited after the solution had stood for 

 some days. The fluate which I used, had been 

 dug out of a lead-mine in Northumberland, and 

 small crystals of sulphuret of lead were here and 

 there to be seen in it. Probably some one of 

 these had escaped my attention, and, by being 

 mixed w 7 ith the fluate which I used, occasioned 

 the appearance of the lead, which, however, did 

 not amount to -3-^-5-th part of the salt, and therefore 

 could not occasion any sensible error in the sub- 

 sequent analysis-. 



