HORTUS GRAMINEUS WOBURNENSIS. 427 



The culms or green straw may be bleached by the process 

 detailed by Mr. Cobbett. The culms being selected and placed 

 in a convenient vessel, boiling water is poured over them, in 

 quantity sufficient to cover the straw ; in this they are to remain 

 ten minutes : when thus scalded, the culms are to be spread out on 

 a grass-plat to bleach; by turning them once a day, the bleaching 

 is generally effected in seven or eight days. According to my 

 experience, the bleaching may be effected in a much shorter 

 space of time. Instead of ten minutes, the culms are suffered to 

 remain in the scalding water from one to two hours; they are then 

 spread out on the grass, and regularly moistened as they become 

 dry, and turned onCe a day for two days : after this it is taken up 

 and washed clean from dust, 8ic. It is then, in a moist state, placed 

 in a close vessel, and subjected to the fumes of burning sulphur 

 for two hours. This has been found sufficient to bleach the straw 

 in the most perfect manner. Green culms, immersed for ten 

 minutes in a strong solution of acetic acid, and then subjected to 

 the sulphureous acid gas, are bleached perfectly white in half an 

 hour. Green culms, immersed for fifteen minutes in muriatic acid 

 diluted with twenty times its measure of water, and then spread 

 on the grass, became in four days as perfectly bleached as those 

 culms which were scalded and bleached eight days on the grass. 

 The texture of the straw was not in the least injured by these pro- 

 cesses. The application of the sulphureous acid gas to the 

 moistened culms,* even after scalding and bleaching or. the grass, 

 had, in every instance, the effect of greatly improving the colour, 

 and that without being productive of the smallest injury to the 

 texture of the straw. 



When straw is immersed in diluted acid it should be whole, for 

 if cut, the acid will get into the hollow of the culm, where it can 

 be of no use to the intention of bleaching. 



To imitate, in the most perfect manner, the Leghorn plait, the 



* It is necessary that moisture should be on the straw during the application of 

 the fumes of sulphur, to obtain the greatest use of the gas ; for water absorbs this 

 gas with rapidity, and the water in this process assists the action of the gas in 

 destroying the colouring matter of the straw without injury to its texture. A liquid 

 sulphureous acid is formed on the surface of the straw during the process. A few 

 laths fixed in the ground, and some others placed crossways, formed a platform for 

 the culms of the grasses in these trials, an iron pan held the burning sulphur, and a 

 large tub inverted on the lath platform confined the fumes of the sulphur to the 

 moistened straw. 



