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however unable to determine, since many different species of this 

 family are clothed with leaves so nearly resembling each other, as 

 not to allow the difference in a single frond to be discovered ; espe- 

 cially when, as in this instance, the surrounding amber prevented 

 a perfect examination; 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 Clusius, or the coronilla herbacea, of Tourne- 

 fort, 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 hqlp of a glass. 



In the Metallotheca of Mercatus is also the representation of 

 what appears to be a small leaf of the coronilla herbacea, flore vario, 

 of Tournefort, or of the onobrychis 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 difficultly 

 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 

 from 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 



* Mem. de 1'Acad. des Sciences, 1743, 



