Natural-Philosophical Collections. 301 
The first object is to procure upon the yarns a good body of chrome yellow, 
of the ordinary and familiar tint of chromate of lead. For this purp pose, the 
goods are well charged with protoxide of lead, which is done by dipping them 
in solution of acetate of lead, and then decomposing the salt by lime-water, of 
which the lime takes the acetic acid, and leaves tne oxide of lead in the cloth. 
Every trace of lime must then be got rid of by washing. 
Ti is necessary to have nothing but oxide of lead in the cloth ; for, with acetate 
or nitrate of lead as the mordant, the colour will be uneven. ‘The goods are 
thea passed through a bath of bichromate of potash, which instantly strikes the 
chrome yellow ofits the oxide of lead. 
The orange is raised by throwing the goods so prepared into lime-water at or 
near a boiling heat. Lime, at that temperature, appears to be capabie of partially . 
decomposing the chromate of lead, taking half the chromic acid from a greater 
or less portion of that salt, and reducing it to the state of dichromate of lead. 
The dichromate of lead is itselfof a full red colour, and is best prepared ac- 
cording to the original process of Mr Badam’s (Aniials of Philosophy, N.S. 
vol, ix.), by digesting a solution of the yellow chromate.of-potash upon carbonate 
of lead at a boiling temperature, in the propertion of one atom of the former to 
two atoms of the latter, stirring up the solid matter very frequently, as the action 
is far from energetic. 
Caustic potash likewise converts the chromate of lead into the dichromate ; 
but, from its strong disposition to dissolve the oxide of lead, as weil as to with- 
draw chromic acid, did not answer with us for forming the dichromate. 
It occurred to Mr R. Ruathen, while engaged with this subject in my labora- 
tory, to try if the dichromate would stand he glazing heat of a potter’s kiln, 
which it was found to do, and to forma pretty good red on ordinary kinds of 
stoneware. Brand’s Journal, Dec. 1829. 
New Vegeto-Alkalies obtained from Cinchona—Dr Serturner, in re-examin- 
ing the products obtained by chemical means from the (enone finds that the 
precipitates produced by alkalies from the acidulated infusion of these barks con- 
tains, besides cinchona and quinia, oiher vegeto-alkalies, which are to be con- 
sidered as modifications of the former. The new bodies recall to mind the case 
of opium, in which narcotine exists simultaneously with morphia. ‘The new 
substances, and especially that named by M. Serturner chiniovdia, exist in the al- 
kaline precipitate, in intimate combination with a resinous subacid substance, 
which is not injurious, but is of no advantage. It is very difficult to separate 
these two substances, and M. Serturner succeeded only when he used the char- 
coal obtained when croconic acid is prepared by Liebeg’s process. This sub- 
Stance, combined with animal charcoal, completely cecolcurs the solution of the 
of the alkaline matter in sulphuric acid (dilutcd with 3 or 4 parts of water), but 
it is necessary afterwards to act on the thick solution with alcohol, to separate 
earthy salts. 
The-new vegeto-alkalies exist in the red and yellow cinchona with the quinia 
and cinchonia. The chinioidia has more alkaline pewer and capacity of satura. 
tion, and also more medical power than any other vegeto-alkali in the cinchona, 
but it resembles them by its insolubility in water, its colour and taste. Its alkaline 
reaction on known vegetable colours, and its intimate state of combination with 
the brown extractive matter are remarkable. [ts salts are very fusible by heat, 
‘and become viscid like some balsams. 
According to M. Serturner, in febrifuge power, chinicida is as superior to 
guinia and cinchonia as these are to ordinary bark. Ii is to this alkali that 
many cinchonas are indebted for their medical Dower: M. Sertumner has, in 
amany cases, given his new medicine in doscs of 2 Gems tliee times per day ; 
the patienis take alittle vinegar after each dose, for the purpose of saturating 
the gastric juice, which, by its alkaline nature, would else decompose the salt 5 
from #2 to 24 vrains have, in all the cases, sniticed to prevent the return of the 
fever, whilst paticnts, in the same neighbourhood, treated with the sulphate of 
quinia, had frequent returns of the disease.—Hufeland’s Journal. 
