380 Clarke and Diller—Topaz from Stoneham, Me. 
of potassium. One preliminary experiment, bearing upon this 
mode of alteration, has been tried. A weighed quantity of the 
topaz, in fine powder, from the sample which was analyzed by 
Mr. Whitfield, was digested on the water bath for seven days 
with a weak solution of potassium carbonate. Then, after 
filtering, the amount of fluorine in the filtrate was estimated, 
é 
Basal section of a Topaz Crystal. 
