UNCOMMON SPECIES' of ZEOLITE. 299 



grains of diftilied water. The powder was immediately attack- 

 ed by the acid ; Tome heat, and momentary effervefcence were 

 produced, and in a few minutes the filex appeared floating 

 in a loofe, and very divided ftate. The mixture being heated 

 on a fand-bath, became in a fhort time a thin transparent jelly. 

 I expofed this jelly to a gentle heat (lefs than 200 ° of Fahren- 

 heit), till it became nearly dry. Water was then poured on it, 

 and the mixture, after being digefhed for fome time, was filter- 

 ed. The undifTolved part collected on the filter, when fuffi- 

 ciently warned, was dried and heated red-hot for a quarter of 

 an hour. It weighed 517 grains, was perfectly white, and pro- 

 ved on examination to be pure filex, unmixed with any other 

 earth. 



2. The filtered folution, which was tranfparent and nearly 

 colourlefs, after being faturated with cauftic ammonia, depo- 

 fited a fmall quantity of a brownifh white precipitate. Having 

 collected this precipitate on a filter, and warned it, I expofed it 

 for a few minutes, to a red heat. It then weighed one grain, 

 and had become brown, and was found to confift of half a 

 grain of oxyd of iron, and half a grain of argil. 



3. In the next place I added a few drops of fulphuric acid to 

 the folution, to difcover if it contained any barytes or fhron- 

 tian. The acid produced no precipitate. The folution was 

 then evaporated to a fmall quantity, and boiled with carbonate 

 of ammonia. Some carbonate of lime was thrown down, 

 which, after being wafhed and expofed for a few minutes to a 

 very low red heat, weighed 57 grains. To drive off the carbo- 

 nic acid, and afcertain the real quantity of lime which this pre- 

 cipitate contained, I put it into a fmall crucible of Cornifh clay, 

 which was inclofed within a Heffian crucible, and heated it for 

 three hours. The fire was raifed flowly at firft, but was after- 

 wards increafed to 8o° of Wedgwood. The lime adhered 



nightly 



