' 1003 



and Holland it has been found, what we should scarcely a priori 

 expect, that muddy, dirty, or stagnant water was most suitable ; and 

 this circumstance is abundantly taken advantage of in Haarlem, Paris, 

 and Lyons. To this circumstance, he thinks, is partially due the 

 celebrity of the dirty stream of the Bievre, or Gobelins, in Paris. 

 Some think that the peculiar action of such water, as a macerant or 

 bath, depends on its saline and other ingredients. Westring and 

 others attribute it to the oxygen which it holds in solution ; this ele- 

 ment apparently being essential to the development of these colouring 

 matters. In proof of the latter view, Westring mentions having 

 noticed that water which had stood a few days in a heated room was 

 no longer suitable for the process of dyeing ; and he throws out a hint 

 that, in the case, at least, of lichens whose colouring matters can be 

 eliminated by cold maceration alone, much brighter and richer tints 

 might be obtained by charging the water with excess of oxygen. 

 The same author also asserts, what we should, at first sight, be less 

 inclined to admit, that the very nature of the atmosphere under which 

 the process is carried on, exercises a most important result on its 

 effects. Whether this depends on the relative amount of oxygen, 

 ammonia, &c., existing in it, or what is the rationale of the phenome- 

 non (assuming it meanwhile to be true). Dr. Lindsay could not at 

 present pretend to say. 



The author concluded his paper by details of a few of his own 

 experiments on the development of lichen colouring-matters, showing 

 how, and to what extent, experiments on the small scale differ from 

 operations on the large scale. His observations were illustrated by 

 a very complete series of lichen-dyes, which he had recently presented 

 to the Museum of Economic Botany at the Royal Botanic Garden. 

 He promised to lay before the Society, at a future meeting, the fur- 

 ther results of his researches on this important subject. 



A number of interesting plants, from the Botanic Garden, were 

 placed on the table ; amongst others, a collection of rare Scotch and 

 foreign alpine plants ; flowering plants of Siphocampylos amoenus, 

 Brachysema acuminata, Schottia laevis, Chorizema superba, and Glox- 

 inia Victoria Reginae, recently presented to the Garden by Messrs. 

 Low & Son, of the Clapton Nursery ; Tagelia bituminosa and Balsa- 

 mina latifolia-alba, presented by Messrs. Henderson & Son, of the 

 Wellington Nursery ; Vriesia speciosa, presented by Messrs. Jackson, 

 of the Kingston Nurseries ; and Cheiranthera linearis, a New-Hol- 

 land plant, with blue flowers, and declinate palmate anthers, presented 



