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II < Obj'ervations on preferving Specimens of Plants. By 

 John Stackhouse, £/^. F.L.S.* 



N profecuting my refearches with a view to complete the 

 hiftor)' of the Britifli Fuci, I was defirous to difcover, if pof- 

 fible, a method of preventing the oHvc-coloured, coriaceous 

 fpecies from turning black in drying. For this purpofe I 

 tried the experiment of immerfing ihem in a ftrong folution 

 of alum. The refult of my experiment did not anfwer my 

 cxpeftation. They were prevented, indeed, from turning 

 black, but they acquired a greenifli hue. However, ima- 

 eininc; this mii»;ht arife from the mixture of aluminous with 

 muriatic falts, and being of opinion that the properties of 

 alum might be of great ufe in prcferving land plants orufe- 

 vcral accounts, I fet on foot a courfe of experiments, and am 

 happy to fay, that the refult has been favourable to my ex- 

 pe6l:alions. After repeated trials, during which partial fail- 

 ures occurred, owing to the proportioning the degrees of 

 ftrength of the folution, and the admiffion of light and air 

 duriiig the time of drying, I can fafely recommend to the 

 public attention the procefs which follows, not doubting but 

 that many improvcmcuts will fuegeft themfclves to thofe who 

 poflcfs a cheniical knowledsie of the various fubllanccs made 

 ufe of by dyers in fixing their colours. 



Take a faturated folution of powdered alum in common 

 •water : immcrfe carefully your fpecimeti, flowers, leaves and 

 ftalk in this liquor. During this immerfion, with a camel's- 

 hair bru{h, fuch as varnifliers make ufc of, wet thoroughly a 

 llieet of blotting-paper : difplay your fpecimen carefully on 

 this paper, and prepare another ilieet in a fimilar manner to 

 lay over vour plant. Then give a fmart prcfl'urc to your 

 plant, either with a botanical prefs, a napkin prefs, or 

 weights of aiiy kind applied to the fpecimen placed between 

 fniooth boards, or books, obferving to lay about half a quire 

 of paper beknv the fpecimen, and the fame quantity above, 

 to lake up the moifturc. Afler a day or two, according to 



• f I'jn: till; Traufu^icya of tb: Lrimvan S'jci'ij, \'ol. V, 



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