a Tef Liquor for Acids and Alkalies. hy Bae 
a few hours, and they will yield a blue liquor, which, if ufed 
immediately as a teft, will be found to poffefs great fenfibility. 
But, as this liquor is very fubjeé& to turn acid and putrid, and 
to lofe its fenfibility, when it is wanted to be preferved for 
future ufe the following proceffes fucceed the beft. 
1. After havx.z minced the leaves, {pread them on paper, 
and dry them in a gentle heat; when perfectly dry, put them 
up in glafs bottles well corked; and when you want to ufe 
them, acidulate fome water with vitriolic acid, and digeft, or 
infufe, the dry leaves in it until they give out their colour; 
then ftrain the liquor through a cloth, and add to it a quan- 
tity of fine whiting or chalk, ftirring it frequently until it 
becomes of a true blue colour, neither inchning to green nor 
purple; as foon as you perceive that it has acquired this colour, 
filter it immediately, otherwife it will become greenifh by 
longer ftanding on the whiting. 
This liquor will depofite a {mall quantity of gypfum, and 
by the addition of a little fpirit of wine will keep good for’ 
fome days, after which it will become a little putrid and red- 
difh. If too much fpirit is added, it deftroys the colour. If 
the liquor is wanted to be kept longer, it may be neutralized by 
means of a fixed alkali inftead of chalk. 
2. But as none of thefe means will preferve the hquor lone 
without requiring to be neutralized afrefh, juft before it is ufed ; 
and as the putrid and acid fermentation which it undergoes, and 
perhaps the alkalies or fptrit of wine mixed with it, feem to: 
lefien. its fenfibility; in order to preferve its virtues while it is. 
kept in aliquid ftate, fome freth leaves cf the cabbage, minced’ 
‘as has been dire&ted, may be infufed in a mixture of vitriolic 
acid and water, of about the degree of acidity of vinegar; and 
it may be neutralized, as it is wanted, either by means of chalk, 
or 
