340 ON Ambergris, &e. 



Ambergris. 



Yellow amber- This piece was found on the coast of Brasil. It is of the 



gris from Bra- , c , , , . • . 



gil, colour or honey; very homogeneous in its texture; and 



free from those fragments or beaks of the cuttlefish, that 

 are interspersed in the ash-coloured amber of the shops. Al- 

 cohol dissolves it entirely, except a few slight pellicles. 

 This solution is curdkd by Avater. Evaporated it leaves 

 a yelloVv substance, which softens and burns like a resin ; 

 swims on a solution of potash, which dissolves but a few 

 atoms of it; and gives out no smell of ammonia. The fra- 

 grance of this purified resin is still that of the ambergrise 

 itself. Exposed to distillation it melts quietly, without 

 swelling up, and yields a thick, yellow oil, which swims 

 on water. It is accompanied with some indications of an 

 acid: but what is astonishing is the ambergris scent of this 

 oil. 



Cochineal* 

 Cochineal acid. The powder of this insect has always seemed to me to 



Its colouring navean ac id taste. I know not whether it be the effect of the 

 jnatfer precipi- . . . 



tated with iime, action of air on any of its principles. JLime water pre- 

 cipitates its colouring matter completely, and the result is a 

 but obtainable lake, on which alcohol has no action. To obtain the pure 



more pure with co i our j nS r principle, we should decompose this lake : but as 



oxide ot tin or •%» , 



jead. the white oxides of tin and of lead likewise saturate them- 



selves with it readily, we may obtain it still more pure from 

 these by means of sulphuretted hidrogen, than by employ, 

 ing acids. I believe the colouring principle of kermes 

 likewise precipitates with lime. 



Ox gall. 

 Resin of gall. Acids precipitate from this a resin, which, after it has 

 been well washed in boiling water, may be drawn into 

 threads like boiled turpentine. When dry, it is semitrans- 

 parent, greenish, melts with the gentlest heat, and on 

 burning coals exhales a smoke that has somewhat of a fra- 

 grant smell. Alcohol dissolves it, without leaving any 

 residuum; and water precipitates this solution. Oxigenized 

 muriatic acid whitens it with the assistance of a gentle heat. 

 It remains in complete fusion, after having given out some 



moisture s 



