£8 Mcmcir upon Coffee. 



iijitic ihc composilion of the coffee from wliich I had sepa- 

 rated the extract and the acid,'8cc. 



We have seen that the 2000 parts lost 280 by the different 

 decoctions they had undergone ; and the residue \vas conse- 

 quently reduced to 1720. I endeavoured to incinerate it 

 by burning it ia a Hessian crucible, which I kept red-hot 

 for an houx : tlic matter began, at first, to spread a pungent 

 smoke, which aflectcd the eyes; inflammation afterwards 

 took place, and the uiatter burned in this nianncr during 

 sonic iTiinutes. The residue of this operation was a very 

 black charcoal, \^•eighing 430 parts; it was reduced into 

 powder and put into a piatina crucible, which I kept red- 

 hot lor two hours in a reverberating furnace. It was only 

 in this manner that I sueccedcd in reducing it to ashes, 

 but still in an imperfect manner, since of 322 parts, which 

 the crucible contained after calcination, 230 only were con- 

 verted into ashes ; 92 parts of a charry matter remaining, 

 wliich refused all attempts at incineration. I poured 20O 

 parts of water upon 'JSO of ashes, and filtered and evaporated 

 the liquor: it furnished as a product ten parts of a saline 

 substance, precipitated the nitrate of silver, in a flaky muri-ate, 

 and which I recognised, after examining it, to be nothing 

 else than muriate of potash. 



The residue was saturated with nitric acid, which entered 

 into eomhination with a slight eflcrvescence, and without 

 leaving any residue. I decomposed the nitrate formed by 

 liic caibonate of potash, and collected the precipitate upon 

 a lillcr; it was carefully washed, and calcined in a-platina 

 crucible; being weighed after this operation there were 216 

 parts of it, which, added to' the ten of the alkaline muriate, 

 yielded 226, frou) which the loss must have amounted to 

 four pari^. Tlie taste ,of this earthy substance was caustic 

 and burning, absorbing water greedily, and with a disen- 

 gagement of heat. According to this, I did ncn hesitate to 

 consider it as caustic lime : in order to ascertain it, how- 

 ever, in a more certain manner, I dissolved it a second time 

 in nitric acid, and tried the liquid nitrate by the sulphuric 

 .iud oxalic acids, which formed in it insoluble precipitates 



of 



