Mr. English on Preservation of Plants. 73 



I then tried petroleum last [i.e., after pressing) instead of 

 first. I found that some kinds of foliage did best in the 

 latter way, but flowers were most successfully dried first, 

 the petroleum being afterwards applied. This I found to 

 be the case almost by accident. I had laid some flowers 

 in the -sun ; of course they soon shrivelled and dried up, 

 but I was surprised with the brilliant colours they re- 

 tained. It occurred to me that heat and a powerful 

 absorbent of moisture might be successfully tried. I took 

 ordinary plaster-of-Paris, warmed to about 90 or 100 degrees 

 (F.), and embedded the fresh flowers in it, shaking the 

 plaster carefully down on the plants. This plan answered 

 admirably. Small plants were preserved in less than twelve 

 hours ; larger species took longer in proportion to the 

 amount of moisture in their tissues. When taken out of 

 the plaster the plants presented a very dusty appearance, 

 and if left in it too long they became somewhat 

 brittle, but on being laid aside in the air for a time they 

 soon relaxed. They were then brushed with a camel's-hair 

 pencil, and petroleum carefully applied with a brush. 

 Such is the history of the specimens now exhibited, show- 

 ing well the natural form and colour. Eeds and purplish- 

 reds, however, came out too purple. I overcame this diffi- 

 culty at last by immersing the dried plants in the vapour 

 of hydrochloric acid. About a teaspoonful of acid is put 

 into a wide-mouthed bottle or glass cylinder, and the plants 

 suspended by the stalks, so as not actually to touch 

 the liquid acid ; when the proper shade of colour appears 

 they must be quickly removed. 



Plants thus dried can be pressed as usual for the herba- 

 rium sheets, or exhibited in cabinets, like collections of 

 insects, and would probably be found extremely useful for 

 educational purposes. Some of the more rigid plants can 

 be mounted under glass shades, and they then have a very 

 pleasing appearance, but exposure to the light is very likely 

 to fade them. 



It may be well to add that, about three weeks since, a 

 gentleman (an artist) called upon me. He had been travel- 

 ling in North America, and when in New York he was 



