J 84 1.] On Lichens. 895 



These are Orc'me. Its taste is sweet and nauseous, it melts readily in a 

 retort into a transparent liquid, and distils without undergoing any 

 changes. It is soluble in water and alcohol. Nitric acid colours it blood- 

 red ; which colour afterwards disappears. Subacetate of lead precipitates it 

 completely. Its conversion into the Archil red is effected by the action 

 of an ^Ikali, in contact with the air. 



When dissolved for example in ammonia and exposed to the atmosphere, 

 it takes a dingy brown-red hue ; but when the Orcine is exposed to air 

 charged with vapours of ammonia, it assumes by degrees a fine violet 

 colour. To obtain this result, the Orcine in powder should be placed in 

 a capsule, alongside of a saucer containing water of ammonia, and both 

 should be covered a large bell-glass ; whenever the Orcine has acquired 

 a dark brown cast, it must be withdrawn from under the bell, and the 

 excess of ammonia be allowed to volatilize. As soon as the smell of 

 ammonia is gone, the Orci?ie is to be dissolved in water; and then a few 

 drops of ammonia being poured into the brownish liquid, it assumes a magni- 

 ficent reddish violet colour. Acetic acid precipitates the red lake of Lichen. 



If the above pages contain a single hint which have escaped the re- 

 searches of your able Curator, or others interested in his researches, 

 I shall be amply repaid for the small trouble of transcribing them, and 



have the honor to remain, 



Sir, 



Your obedient servant, 



Dehlee,5th October, 1841. Henry Cope. 



A Fourth Memoir on the Law of Storms in India, being remarks and 

 documents relative to the loss of the Ship Golconda, in the Tyfoons 

 of 22nd to 2Ath September 1840, in the China Sea. By Henry 

 PiDDiNGTON, Esq. 



This memoir has arisen out of a question proposed to me by Mr. 

 Greenlaw, the active Secretary to the Marine Board, which was in sub- 

 stance this : " On what day do you think the Golconda was lost"? I found 

 that the investigation which I undertook in order to reply to it with 

 greatest possible precision, elicited facts of so much importance that 

 they might be worth publication as a separate memoir; not only as 

 records distinctly shewing the truth of the Law of Storms for the 

 China Seas, but as affording to seamen a valuable practical lesson ; for 



