ie T : IV. Olferations on ri Specimens of Plants, 
ne d John Stack fe Fit ELS, 
a — 798 
"N profecuting my refearches with a view to complete the hiftory 
of the Britifh Fuci, I was defirous to difcover, if poffible, a me- - 
thod of preventing the olive-coloured, coriaceous fpecies from turn- 
ing black in drying. For this purpofe I tried the experiment of im- 
merfing them i In a ftrong folution of alum. The refult of my ex- 
. periment. did not. anfwer my expectation. They were prevented. 
indeed from turning black, but they acquired a greenifh hue. How- 
ever, imagining this might arife from the mixture of aluminous 
with muriatic falts, and being of opinion that the properties of alum 
Rt ufe i in Dru land plants on feveral accounts, 
experiments, and am happy | to fay that the 
has A. e to my expectations. After repeated trials, 
daring which partial failures occurred, owing to the proportioning 
the degrees of ftrength of the folution, and the admiflion of . light 
and air during. the time of drying, I can fafely recommend to the 
public attention the procefs which follows, not doubting but. that 
many impr: ovements will fuggeft themfelves to thofe who poflefs a a 
chemical knowledge of the various fubftances made ue of. P dyers 
in fixing their colours. UL E 
-Take a faturated folution of powdered alum in common Water ; 
immerfe carefully your fpecimen, flowers, leaves and falk, in this 
liquor. 
