34 } 6 Afr. Gregor’s Experiments on a mineral Substance 
centre. They were, in general, colourless : a few of them were 
tinged of a smoke-colour. They soon became deliquescent. 
Upon evaporation, the same crystallizations were produced. 
After a time, some detached, regular, and permanent crystals 
were formed, which were colourless. Their figure I could not 
accurately ascertain. They were exposed to a red heat in a 
platina crucible. No ammoniacal vapour was perceptible. The 
crystals melted into opaque globules : some of these were 
transferred to a small glass, and distilled water was poured 
upon them. No solution took place, apparently : on shaking 
the glass, the globules fell to pieces into gelatinous flakes, which 
were white. Some of the supernatant fluid was tried with 
muriate of barytes, which produced a cloud. But neither am- 
monia nor prussiate of potash caused any change in it. It is 
soluble also in nitric acid : the solution formed a confused crys- 
tallized mass, which soon became deliquescent. Zinc, immersed 
in it, caused the separation of white gelatinous flakes. Iron 
caused no change. Ammonia and potash threw down white 
precipitates, a portion of which were redissolved. The carbo- 
nates of soda, potash, and ammonia produced white precipitates. 
Prussiate of potash threw down the contents of the solution in 
distinct flakes, of the colour of mahogany ; and the solution of 
galls in alcohol caused a light yellow powder to subside. It is 
soluble also in muriatic acid; the solution is a very dilute green. 
It requires an excess of acid to hold the substance in solution ; 
which, after a time, deposits crystalline grains of a yellowish 
colour, which require a large quantity of water to dissolve them. 
Acetic acid does not dissolve this powder. 
( 8. ) What was dissolved by potash ( 3. ) was of an Isabella 
colour : it was tried with nitric, muriatic, and sulphuric acids. 
