ON THE CONSTITUENTS OF LACTUCARIUai. 
59 
This is the principle and mode of putting it in practice ; 
but its success depends upon the skill and experience of the 
operator. For instance, the silver must be dissolved in very 
dilute acid, and slowly precipitated, and the metallic preci- 
pitate nuist be well washed. The silver is then laid upon 
the porcelain before being coloured (or, if coloured, the 
colour must not be any preparation of gold,) in a pasty 
state, and left for twenty-four hours, at the expiration of 
which time the gold is to be laid on, and the article fired at 
a moderate heat. — Idid.y from Bulletin de la Sodttc 
(P Encouragement. 
ART. XVII.— ON THE CONSTITUENTS OF LACTUCARTUM, 
By M. Ludwig. 
The lactucone recently described by Lenoir is, according 
to Walz, nothing more than the lactuca fat examined by 
the latter. Thieme has likewise examined the body which 
is removed by ether from the alcoliolic extract; but he 
could not succeed in separating it, as stated by Walz, into 
a fat easily soluble in ether, and one of sparing solubility in 
that medium, on which account he named it lacincerine. 
Ruickoldt obtained lactucerine by frequent extraction of the 
lactucarium with absolute alcohol, evaporation, washing 
the crystals so obtained with water, re-solution in absolute 
alcohol, again rinsing the crystals with water, and desicca- 
tion under the air-pump. The lactucarium employed by 
the author for the preparation of lactucerine had been col- 
lected in the neighbourhood of Ilten near Hanover, It was 
