^lyO Vegetable Principle eoniatned in Coffee, 



with aflTcrting that this very rare phaenomenon had been ob* 

 fcrved fince the period of Ariftotle only eleven times, and in 

 Germany only once, by Weidler, in 1719. 1 can, however, 

 produce two inftanccs of a lunar rainbow fecn in Germany. 

 In the year 1799 or 1798 I obferved in Pomerania, at a vil- 

 lage in the neighbourhood of Wollin, a rainbow of this kind, 

 even though the moon was not full. If my memory does 

 not fail me, it was then a mild harveft evening, and at moft 

 only eight o'clock. The fky was pretty clear, and the moon 

 was about 30 or 40 degrees above the horizon towards the eaft. 

 Towards the weit I obferved a cloud at about the fame height, 

 and in this was feen the rainbow, the colours of which were 

 exceedingly lively. Its ends only were pale, and very faint. 

 It was larger than a quadrant, but did not form a complete 

 femi-circle. The livelinefs of the colours did not long con- 

 tinue after it was firft obferved ; for a wed wind drove the 

 cloud before it, and a fmall fliower fell. In the month of 

 06lober 1798, about eleven at night, I faw a fecond lunar 

 rainbow, daring a ftiower, in a field of Joachimfthal. The 

 moon was in the ealtern quarter, and at a confiderable eleva- 

 tion. The extent of this rainbow was about 180 degrees, 

 iand it ftood with both its extremities on the ground. Its 

 colours, however, were exceedingly faint ; but the refra6lion 

 was fo apparent, that a fecond pale rainbow was obferved 

 near to it. I have mentioned thefe two obfervations to fliow 

 ihat it is improper to fiy that ihefe phjenomena feldom oc- 

 cur ; we ought only to fay that they have been feldom deli- 

 neated and made known. If the friends of natural philofophy 

 could make obl'ervations in every place where fuch phasno- 

 tnena occur, or were thofe feen by accidental obfervers, who 

 often, through indifference, confider fuch things as hardly 

 ■worth notice, communicated to them, there is no doubt that 

 Iny aiTertion would be confirmed. 



LlX' -Note upon -a frculiar Vegetable Principle contained 

 in C((Q'i£. £^ RicHAiuj Chemevix, Efq. t\R.S, 

 M^H.L A* 



1 



N a velTel calculated to confine the vapour of water, I 

 Jlieated a confiderable portion of that liquid upon about a 

 ipoun^ of ra^v coffee imported dircdlly from Martinic^, and 

 i*f the qualaieri of which I was well aflured. I then fikercd 

 ■tb« liK^'Uvr, aud reduced it nearly to<Jrynefs, in a glafs -ts'-a- 



■* Comrnunicated bjf tlic Author. 



poratln^ 



