154 
to determine, since many diiferent species of this family are clothed 
with leaves so nearly resembling each other, as not to allow the dif- 
ference in a single frond to be discovered ; especially when, as in 
this instance, the surrounding amber prevented a perfect examina- 
tion ; so that, even with the aid of a magnifying glass, the veins of 
the leaf could not be seen. The plant, however, to which it appears 
to approach the nearest, is, he thinks, the securidaca secunda, of Clu- 
sius, or the coronilla herhacea, of Tournefort, which is very common 
in the fields of Prussia. On the one side of the frond was a small 
fly, and on the other a spider ; but neither of them were perceptible 
without the help of a glass. 
In the Metallotheca of Mercatus is also the representation of 
what appears to be a small leaf of the coronilla herhacea, Jlore vario, 
of Tournefort, or of the onohrychis secunda, Clusii, which is also very 
frequently found in the Prussian fields. 
Agricola had observed, two or three hundred years ago, that by 
the distillation of amber it was resolved partly into an oil, bearing a 
similar colour with amber, and partly into a dark bitumen, which, 
he remarks, so much resembles the bitumen of Judaea, as difiicultly 
to be distinguished from it. 
Mons. Bourdelin^ relates some experiments which he made with 
this substance; amongst which the most worthy of notice is, that 
fi-om two pounds of amber he obtained only eighteen grains of earth. 
He discovered the presence of an acid, which he imagined to be the 
muriatic. 
It is now known that amber yields by distillation, first an insipid 
phlegm, then a weak acid, which in the opinion of Scheele is the 
acetous acid, after this a volatile salt arises, and attaches itself to 
the sides of the receiver, and the neck of the retort. This salt was 
first discovered to be of an acid nature by the Hon. Mr. Boyle, and 
.1 ; . 1 
* Mem. de TAcad. des ScienceSj 1743. 
